document.write( "Question 161503: The sum of two numbers is 15. Three times one of the numbers is 11 less than 5 imes the other. The answer is 7 and 8. I just don't know how to set it up to solve. \n" ); document.write( "
Algebra.Com's Answer #118965 by gonzo(654) ![]() You can put this solution on YOUR website! x = 1 of the numbers \n" ); document.write( "y = the other number \n" ); document.write( "----- \n" ); document.write( "sum of the numbers equals 15 in equation form becomes \n" ); document.write( "x + y = 15 \n" ); document.write( "three times one of the numbers equals 11 less than 5 times the other number in equation form becomes \n" ); document.write( "3*x = 5*y - 11 \n" ); document.write( "----- \n" ); document.write( "two equations to be solved simultaneously are: \n" ); document.write( "x + y = 15 \n" ); document.write( "3*x = 5*y - 11 \n" ); document.write( "----- \n" ); document.write( "in the second equation, subtract 5*y from both sides to get \n" ); document.write( "3*x - 5*y = -11 \n" ); document.write( "equations are now both in the same form of a*x + b*y = c reproduced below. \n" ); document.write( "x + y = 15 \n" ); document.write( "3*x - 5*y = -11 \n" ); document.write( "----- \n" ); document.write( "multiply both sides of the first eqution by 3 to get \n" ); document.write( "3*x + 3*y = 45 \n" ); document.write( "3*x - 5*y = -11 \n" ); document.write( "subtract the second equation from the first equation to get \n" ); document.write( "0*x + 8*y = 56 \n" ); document.write( "effectively removing x from the equation to allow you to solve for y. \n" ); document.write( "this becomes \n" ); document.write( "8*y = 56 \n" ); document.write( "which becomes \n" ); document.write( "y = 7 \n" ); document.write( "----- \n" ); document.write( "original first equation is \n" ); document.write( "x + y = 15 \n" ); document.write( "substituting 7 for y, we get \n" ); document.write( "x + 7 = 15 \n" ); document.write( "subtracting 7 from both sides of the equation, we get \n" ); document.write( "x = 15 - 7 \n" ); document.write( "which becomes \n" ); document.write( "x = 8 \n" ); document.write( "----- \n" ); document.write( "second original equation is \n" ); document.write( "3*x = 5*y - 11 \n" ); document.write( "substituting 7 for y and 8 for x, we get \n" ); document.write( "3*8 = 5*7 - 11 \n" ); document.write( "24 = 35 - 11 \n" ); document.write( "24 = 24 \n" ); document.write( "proving the values for x and y are correct. \n" ); document.write( "----- \n" ); document.write( "answers are: \n" ); document.write( "x = 8 \n" ); document.write( "y = 7\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |