Answer:
First mechanic: 20 hours
Second mechanic: 15 hours
Explanation:
First we create two equations where:
x - hours of first mechanic
y - hours of second mechanic
x+y=35
115x+45y=2975
Then, we multiply both sides of the first equation by 45, and then subtract it from the second equation:
45x+45y=1575
|115x+45y=2975
-|45x+45y = 1575
70x = 1400
x=20 hours
Now we know for how many hours the first mechanic worked. Now we just need to subtract that from the combined total to find the second mechanic's hours:
35-20=15 hours