Answer:
First mechanic worked 20 hours and second mechanic worked 5 hours
Explanation:
Let the number of hours the first mechanic worked =

Let the number of hours the second mechanic worked =

Therefore, we can write 2 equations and then solve them simultaneously:


Rearranging the first equation:

and substituting into the second equation to find
:


Now sub
into the first equation to find


Therefore, first mechanic (a) worked 20 hours and second mechanic (b) worked 5 hours