document.write( "Question 1208264: Peter can mow a lawn in 40 minutes. John can mow the same lawn in 60 minutes. How long will it take them to mow the lawn together? \n" ); document.write( "

Algebra.Com's Answer #846589 by greenestamps(13198) $\"\"$ $\"About$

You can put this solution on YOUR website!

\n" ); document.write( "You have received solutions from other tutors showing a couple of different ways of solving this kind of problem. Here is another method.

\n" ); document.write( "Consider the least common multiple of the two given times, which is 120 minutes.
\n" ); document.write( "In 120 minutes, Peter could mow 120/40 = 3 of these lawns; in 120 minutes John could mow 120/60 = 2 of these lawns.
\n" ); document.write( "So together in 120 minutes the two of them could mow 3+2 = 5 of these lawns; and that means that together the two of them can mow the one lawn in 120/5 = 24 minutes.

\n" ); document.write( "This kind of problem (2 workers working together) is very common on tests in timed math competitions. For a shortcut to get you to the answer quickly without having to do formal algebra, the answer is

\n" ); document.write( "(product of the two times) divided by (sum of the two times)

\n" ); document.write( "For this problem: $\"%2840%2A60%29%2F%2840%2B60%29=2400%2F100=24\"$

\n" ); document.write( " \n" ); document.write( "

\n" );