Answer:
he first one worked 15 hours, the second one worked 5 hours.
Step-by-step explanation:
First mechanic worked x hours, then second one worked 20 - x hours
First one charged $95*x, second one charged $75*(20-x)
Total charge = 95x + 75(20 - x) = 1800
95x + 1500 - 75x = 1800
20x = 300
x = 15, 20 - x = 5
So the first one worked 15 hours, the second one worked 5 hours.