Set A consists of the integers from 4 to 15, inclusive, while set B consists of the integers from 6 to 20, inclusive. How many distinct integers do belong to the both sets at the same time?	Choose the correct choice from the following choices:
A) 5 B) 7 C) 8 D) 9 E) 10

Rationale: a = { 4,5 , 6,7 , 8,9 , 10,11 , 12,13 , 14,15 } b = { 6 , 7,8 , 9,10 , 11,12 . . . 20 } thus we see that there are 10 distinct integers that are common to both . e is the correct answer .
Answer: E