(I will mark brainliest if correct)
Matt has started a car washing business to save money for college. each week he washes three more cars than the week he did before.

Part A: Matt started by washing 6 cars his first week in business. Write an explicit formula that can be used to find the number of cars he washed on any given week.
A. 6+3n
B. 6(3n-1)
C. 6+3(n-1)
D. 3+6(n-1)
Part B: How many cars will Matt wash on his 11th week in business?
A. 17
B. 36
C. 39
D. 66

(if you don't want to answer part B I just really need Part A but it would be very helpful if you did both parts)