Question #f5a07

1 Answer
Jan 5, 2017

First, we must find out how much of the job remains and then how long the two will need.

Explanation:

The first sec. worked for 2 hours and so completed a fraction 2/8=1/4 of the job, leaving 3/4 of the job to do.
If they now both work for x hours, the first will complete x/8 of the job and the second x/10.
So we need to solve 3/4=x/8+x/10.

Multiplying both sides by 40 gives 30=5x+4x=9x.
And so x=10/3 hours or 3 hours and 20 minutes.