At the Zoo

This task is about how many times a number divides into another number with a remainder.
illustration: the zoo
 
Because of a celebration at the zoo, every 7th adult going through the gate was allowed in free.
645 adults have gone through the gate.

Question 2Change answer

a)  How many adults went through the gate free? 

Question 2Change answer

b)  After 645 adults have gone through the gate, the next free admission would be the adult.