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

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