Question

4. A plumber charges a flat rate of $50 and $25 an hour for the work. The plumber received $150 for his services. How many hours did the plumber work?

Answer 1

The plumber worked 4 hours.

Answer 2

He gets $25 per hour and receives $150 for the work. 

150 (earnings) / 25 (per hour) = 6

The plumber worked for 6 hours.

(if you still don't understand something, I'm all ears! :)