Question 101481
Let's call the apprenctice's salary x per hr. Thus the plumber makes x + 4.50 per hr. In the course of the day, they earn a combined: 8 * (x + x + 4.5) = 16x + 36.
We also are told their total wages are $372.  So, 16x + 36 = 372.  Subtracting 36 from both sides, we have 16x = 336.  Dividing both sides by 16, we have x = 21. that means the apprentice is paid $21 per hr, and the plumber is paid $25.50.

ALWAYS check your computation!  So, 8 * 21 = 168 paid to the apprentice; and 8 * 25.5 = 204.  Adding these we have 168 + 204 = 372. Check.