A certain airline's fleet consisted of 80 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?	Choose the correct choice from the following:
A) 9	B) 10	C) 11	D) 12	E) 13
Let x be the number of years.   4x &gt; 80 - 3x   7x &gt; 80   x &gt; 11 + 3/7   The answer is 12.
<result>D</result>
A certain airline's fleet consisted of 80 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?