The average of a set of 7consecutivr positive intergers is 15. What is the sum of the three smallest numbers in that set?

A) 38
B) 39
C) 42
D) 48
E) 51

(B)

the numbers must be evenly arranged above and below 15, so they must be

12,13,14,(15),16,17,18

12+13+14 = 39