For each situation, write the equation to represent each situation. then use your equation to answer each question. be sure to define your variables, identifying which is independent and which is dependent. show all work. round any decimals to the nearest hundredth and choose the correct answer from the choices below.

a plumber charges a customer 60 dollars an hour plus the price of any parts needed to complete the work. if the total bill is 240 dollars and just the parts alone cost 90 dollars, how long did it take to complete the work?

a) 2.5 hours

b) 300 minutes

c) 6.17 hours

d) 4 hours