document.write( "Question 269702: The time it takes to do homework includes a fixed amount of time to prepare plus a constant amount of time per problem. If a student can do 5 homework problems in 40 minutes, and 10 problems in 70 minutes, how many minutes will 25 problems take? \n" ); document.write( "

Algebra.Com's Answer #197622 by mananth(16946) $\"\"$ $\"About$

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The time it takes to do homework includes a fixed amount of time to prepare plus a constant amount of time per problem. If a student can do 5 homework problems in 40 minutes, and 10 problems in 70 minutes, how many minutes will 25 problems take?\r
\n" ); document.write( "\n" ); document.write( "Let the fixed time taken be x\r
\n" ); document.write( "\n" ); document.write( "The time to solve a problem be y\r
\n" ); document.write( "\n" ); document.write( "x+5y=40------------1
\n" ); document.write( "x+10y=70-----------2\r
\n" ); document.write( "\n" ); document.write( "subtract equation 2 from 1\r
\n" ); document.write( "\n" ); document.write( "(x+5y) - (x+10y) = 40-70\r
\n" ); document.write( "\n" ); document.write( "x+5y -x-10y = -30\r
\n" ); document.write( "\n" ); document.write( "-5y=-30
\n" ); document.write( "y=-30/-5
\n" ); document.write( "y=4. Time taken to solve each problem is 4 minutes\r
\n" ); document.write( "\n" ); document.write( "x+5y=40 substitute the value of y in the equation\r
\n" ); document.write( "\n" ); document.write( "x+20=40\r
\n" ); document.write( "\n" ); document.write( "x=40-20 = 20 minutes will be the fixed time \r
\n" ); document.write( "\n" ); document.write( "25 problems will take (20 minutes + 4 *25)
\n" ); document.write( "= 120 minutes or 2 hours\r
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