document.write( "Question 251225: I have $2.35 in nickles and dimes . If i have a total of 23 coins , how many of each coin do i have ? \n" ); document.write( "
Algebra.Com's Answer #182940 by oberobic(2304)![]() ![]() ![]() You can put this solution on YOUR website! In solving coin problems, you have to keep track of the number of coins and the value of the coins. \n" ); document.write( "n = number of nickels \n" ); document.write( "5n = value of the nickels in cents \n" ); document.write( "d = number of dimes \n" ); document.write( "10d = value of the dimes in cents \n" ); document.write( ". \n" ); document.write( "We are told n+d = 23 coins. \n" ); document.write( "We are told that 5n + 10d = 235 cents. \n" ); document.write( ". \n" ); document.write( "We can solve these two equations in several ways. An obvious approach is to set n = 23-d and then substitute. \n" ); document.write( ". \n" ); document.write( "5(23-d) + 10d = 235 \n" ); document.write( "115 - 5d + 10d = 235 \n" ); document.write( "5d = 120 \n" ); document.write( "d = 24 \n" ); document.write( ". \n" ); document.write( "n + d = 23 \n" ); document.write( "n = -1 \n" ); document.write( ". \n" ); document.write( "Checking our values: \n" ); document.write( "5n = 5*-1 = -5 cents \n" ); document.write( "24d = 10*24 = 240 cents \n" ); document.write( "Adding: 235 cents. \n" ); document.write( ". \n" ); document.write( "But this is a nonsensical answer. You cannot have -1 nickels. \n" ); document.write( ". \n" ); document.write( "Using a 'brute force' approach, it is easy to see that the maximum value of 23 coins occurs with 22 dimes and 1 nickel...and it is 225 cents ($2.25), which is less than the stated amount. \n" ); document.write( ". \n" ); document.write( " \r\n" ); document.write( "n d n+d 5n 10d 5n+10d\r\n" ); document.write( "1 22 23 5 220 225\r\n" ); document.write( "2 21 23 10 210 220\r\n" ); document.write( "3 20 23 15 200 215\r\n" ); document.write( "4 19 23 20 190 210\r\n" ); document.write( "5 18 23 25 180 205\r\n" ); document.write( "6 17 23 30 170 200\r\n" ); document.write( "7 16 23 35 160 195\r\n" ); document.write( "8 15 23 40 150 190\r\n" ); document.write( "9 14 23 45 140 185\r\n" ); document.write( "10 13 23 50 130 180\r\n" ); document.write( "11 12 23 55 120 175\r\n" ); document.write( "12 11 23 60 110 170\r\n" ); document.write( "13 10 23 65 100 165\r\n" ); document.write( "14 9 23 70 90 160\r\n" ); document.write( "15 8 23 75 80 155\r\n" ); document.write( "16 7 23 80 70 150\r\n" ); document.write( "17 6 23 85 60 145\r\n" ); document.write( "18 5 23 90 50 140\r\n" ); document.write( "19 4 23 95 40 135\r\n" ); document.write( "20 3 23 100 30 130\r\n" ); document.write( "21 2 23 105 20 125\r\n" ); document.write( "22 1 23 110 10 120\r\n" ); document.write( " \n" ); document.write( ". \n" ); document.write( "So there is no solution to the problem. \n" ); document.write( " |