document.write( "Question 1152784: Roger has 27 standard U.S. coins worth a total of $3.65. No coin is worth more than 30¢ or less
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document.write( "than 3¢. How many dimes could Roger have? (NOTE: There are several possible answers, but
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document.write( "you only need to give TWO correct answers.) \n" );
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Algebra.Com's Answer #774877 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "List out the various coins \n" ); document.write( "{penny, nickel, dime, quarter, half dollar, silver dollar} \n" ); document.write( "We are told that no coin is less than 3 cents, so we can cross off the penny \n" ); document.write( "{ \n" ); document.write( "leaving us with this set \n" ); document.write( "{nickel, dime, quarter, half dollar, silver dollar}\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "and we are also told that no coin is worth more than 30 cents, so we can cross off the half dollar and silver dollar coins \n" ); document.write( "{nickel, dime, quarter, \n" ); document.write( "leaving us with \n" ); document.write( "{nickel, dime, quarter}\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore, the coins we're dealing with are: {nickel, dime, quarter}\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "n = number of nickels \n" ); document.write( "d = number of dimes \n" ); document.write( "q = number of quarters\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "n+d+q = 27 because we have 27 coins \n" ); document.write( "Solve for q to get q = 27-n-d\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "5n = value, in cents, of all the nickels \n" ); document.write( "10d = value, in cents, of all the dimes \n" ); document.write( "25q = value, in cents, of all the quarters \n" ); document.write( "5n+10d+25q = total value of all the coins \n" ); document.write( "total value = 365 cents = 3.65 dollars \n" ); document.write( "5n+10d+25q = 365\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "5n+10d+25q = 365 \n" ); document.write( "5n+10d+25(27-n-d) = 365 ... plug in q = 27-n-d \n" ); document.write( "5n+10d+25(27)+25(-n)+25(-d) = 365 ... distribute \n" ); document.write( "5n+10d+675-25n-25d = 365 \n" ); document.write( "-20n-15d+675 = 365 \n" ); document.write( "-20n-15d+675-675 = 365-675 ... subtract 675 from both sides \n" ); document.write( "-20n-15d = -310 \n" ); document.write( "-5(4n+3d) = -310 \n" ); document.write( "4n+3d = 62 .... divide both sides by -5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now solve for n \n" ); document.write( "4n+3d = 62 \n" ); document.write( "4n = -3d+62 \n" ); document.write( "n = (-3d+62)/4 \n" ); document.write( "n = (-3d+2+60)/4 \n" ); document.write( "n = (-3d+2)/4+60/4 \n" ); document.write( "n = (-3d+2)/4+15 \n" ); document.write( "Through trial and error, you'll find that d = 2 makes the expression (-3d+2)/4 result in an integer \n" ); document.write( "n = (-3d+2)/4+15 \n" ); document.write( "n = (-3*2+2)/4+15 \n" ); document.write( "n = (-6+2)/4+15 \n" ); document.write( "n = -4/4+15 \n" ); document.write( "n = -1+15 \n" ); document.write( "n = 14 \n" ); document.write( "So we have d = 2 dimes pair up with n = 14 nickels.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If d = 2 and n = 14, then, \n" ); document.write( "q = 27-n-d \n" ); document.write( "q = 27-2-14 \n" ); document.write( "q = 11\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "--------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now increase d = 2 to d = 6. This is an increase of +4, which is from the denominator of 4 in (-3d+2)/4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We have, \n" ); document.write( "n = (-3d+2)/4+15 \n" ); document.write( "n = (-3*6+2)/4+15 \n" ); document.write( "n = (-18+2)/4+15 \n" ); document.write( "n = -16/4+15 \n" ); document.write( "n = -4+15 \n" ); document.write( "n = 11\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now use n = 11 and d = 6 to get, \n" ); document.write( "q = 27-n-d \n" ); document.write( "q = 27-11-6 \n" ); document.write( "q = 10\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Two solutions are \n" ); document.write( "(n,d,q) = (14,2,11) \n" ); document.write( "and \n" ); document.write( "(n,d,q) = (11,6,10)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "For the solution (n,d,q) = (14,2,11), we can say \n" ); document.write( "5n = 5*14 = 70 cents is from the nickels only \n" ); document.write( "10d = 10*2 = 20 cents is from the dimes only \n" ); document.write( "25q = 25*11 = 275 cents is from the quarters only \n" ); document.write( "5n+10d+25q = 70+20+275 = 365 cents = $3.65 is the total combined value \n" ); document.write( "This confirms the solution (n,d,q) = (14,2,11)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "For the solution (n,d,q) = (11,6,10), we can say \n" ); document.write( "5n = 5*11 = 55 cents is from the nickels only \n" ); document.write( "10d = 10*6 = 60 cents is from the dimes only \n" ); document.write( "25q = 25*10 = 250 cents is from the quarters only \n" ); document.write( "5n+10d+25q = 55+60+250 = 365 cents = $3.65 is the total combined value \n" ); document.write( "This confirms the solution (n,d,q) = (11,6,10)\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There are 5 total ways to have nickels, dimes, and quarters combine to $3.65 such that we have 27 coins total \n" ); document.write( "
\n" ); document.write( "Each row adds to 27. \n" ); document.write( "The solutions we found earlier are in cases D and E of this table.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So Roger could have 6 dimes (case D) or he could have 2 dimes (case E). \n" ); document.write( " \n" ); document.write( " |