4. A plumber charges $45 per hour plus a $25 service charge. If a represents his total charges in dollars and b represents the number of hours worked, which formula below could the plumber use to calculate his total charges? (A-CED.1)
A. a = 45 + 25b
B. a = 45 + 25 +b
C. a = 45b + 25
D. a = (45) (25) + b

C. a=45b + 25

Step-by-step explanation:

It would be C

Step-by-step explanation:

a = 45b + 25

Reason:

It says the plumber charges 45 dollars per hour and that b is the number of hours worked. so we multiply 45 dollars by the variable b(number of hours worked), then we add the service charge, since the service charge is only added once, we do not multiply it by a variable.

Therefore we get:

a = 45b + 25