Answer:
40
Explanation:
There is enough information, so D is not an answer.
10 is far to low. The number is roughly 40. So A is not the answer.
16/20 = .80 that recommended the tooth paste. If you stopped there, 40 would be your answer. But they took one more survey.
24/30 = .80
So both groups come back with an amount that = 0.8
That means that you should pick 40 as your answer.