Problem: set a consists of the integers from 4 to 16 , 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 ?
Rationale: "a = { 4 , 5,6 , 7,8 , 9,10 , 11,12 , . . . 16 } b = { 6 , 7,8 , 9,10 , 11,12 . . . } thus we see that there are 11 distinct integers that are common to both . e is the correct answer ."
annotated_formula: add(6, 4)