A certain airline's fleet consisted of 110 type A planes at the beginning of 1980. At the end of each year, starting with 1980, the airline retired 3 of the TYPE A planes and acquired 4 new type B plans. How many years did it take before the number of type A planes left in the airline's fleet was less than 50 percent of the fleet?  Options:
A) 15
B) 16
C) 17
D) 18
E) 19

Rationale: let x be the number of years . 4 x > 110 - 3 x 7 x > 110 x > 15 + 5 / 7 the answer is b .
Answer: B