Answer:
It would be C
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