What is the sum of all positive integers less than 100 that are divisible by both 3 and 5?
Correct: B
Integers divisible by both 3 and 5 are divisible by their least common multiple, which is 15. The multiples of 15 less than 100 are 15, 30, 45, 60, 75, 90. Their sum is 15 + 30 + 45 + 60 + 75 + 90 = 315.