Answer:
8 people got gumballs out of the machine.
Explanation:
Given that:
Number of gumballs in machine = 78
Number of gumballs on each coin = 3
Number of gumballs left = 54
Let,
x be the number of people who put coin
Gumballs left = Total gumballs - 3*Number of people
54 = 78 - 3x
3x = 78 - 54
3x = 24
Dividing both sides by 3

Hence,
8 people got gumballs out of the machine.