im having trouble with this math question

Question

A survey of new Toyota Corolla owners has shown that during the first year of ownership, 15% of Corollas required repairs once, 7% required repairs twice, and 5% required repairs three or more times. Suppose you are interested in purchasing one.

(a) What is the probability that your new car won't require any repairs during the first year?

Answer: 

(b) What is the probability that your new car will need repairs no more than once during the first year?

Answer: 

(c) What is the probability that at least one repair will be required during the first year?

Answer: 

Answer 1

a) 100-15-7-5 = 73%

b) 100-7-5 = 88%

c) 100-73= 27%