Ere are 30 boys in a sporting club, 20 of them play hockey, 15 at least one of the two game

5 boys play all the two games

25 boys play only one game

Step-by-step explanation:

Sets

There are two sets defined in the question: one for the boys who play hockey (H) and the other for the boys who play volleyball (V).

All the boys play at least one of the two games, so no elements are outside both sets.

There are 30 boys in total. 20 of them play hockey and 15 play volleyball. Since the sum of both numbers is greater than the total of boys, the difference corresponds to the boys who play both games.

Thus 20 + 15 - 30 = 5 boys play both games

Given that 5 boys are shared by both sets, from the 20 playing hockey, 15 play ONLY hockey. From the 15 boys playing volleyball, 10 play ONLY volleyball.

Thus 15 + 10 = 25 boys play only one game.

The Venn diagram is shown in the image.

this doesn't support enough information to answer the question.

the telephone is the answer