Answer:
Correct answer: First x = 15 h and second y = 5 h
Step-by-step explanation:
To solve this problem we will form a system of two equations with two variables:
Let be the time of the first mechanic x  and of the second y
x + y = 20  ⇒ y = 20 - x
85 x + 80 y = 1675
85 x + 80 (20 - x) = 1675
85 x + 1600 - 80 x = 1675
5 x = 1675 - 1600
5 x = 75
x = 75 / 5 = 15 h
x = 15 h
y = 20 - 15 = 5 h
y = 5 h
God is with you!!!
