A is 10th from the top, B is 15th from the bottom. C is 18th from the top. If C is exactly between the two, then how many persons are there?

38 42 40 35

40

10 persons till A 7 persons between A and C 1 person C himself 7 persons between C and B  15 persons B and thereafter So, total is : 10 + 7 + 1 + 7 + 15 = 40