document.write( "Question 1184557: Two mechanics worked on a car. The first mechanic charged $105 per hour, and the second mechanic charged $50 per hour. The mechanics worked for a combined total of 20 hours, and together they charged a total of $1825. How long did each mechanic work? \n" ); document.write( "
Algebra.Com's Answer #815171 by greenestamps(13208) You can put this solution on YOUR website! \n" ); document.write( "First a traditional algebraic setup for solving the problem.... \n" ); document.write( "x = hours at $105 per hour \n" ); document.write( "20-x = hours at $50 per hour \n" ); document.write( "Total charge for 20 hours was $1825: \n" ); document.write( " \n" ); document.write( "Solve using basic algebra. \n" ); document.write( "And a solution method without algebra, using logical reasoning and some mental arithmetic.... \n" ); document.write( "All 20 hours at $105 per hour would cost $2100; all 20 hours at $50 per hour would cost $1000; the actual cost was $1825. \n" ); document.write( "Look at the three costs on a number line -- 1000, 1825, and 2100 -- and observe/calculate that 1825 is 825/1100 = 3/4 of the way from 1000 to 2100. \n" ); document.write( "That means 3/4 of the hours were at the higher rate. \n" ); document.write( "ANSWER: 3/4 of 20 hours, or 15 hours, at $105 per hour; the other 5 hours at $50 per hour \n" ); document.write( "CHECK: 15(105)+5(50)=1575+250=1825 \n" ); document.write( " \n" ); document.write( " |