Answer: 13
Step-by-step explanation
Add up the expressions in the circles.
(22-y) + (y) + (14-y) = 36 - y
This is the number of people who either own a bike, a surfboard, or both.
Add on the 2 people that own neither to get 36-y+2 = 38-y
There are 38-y total members.
Set this equal to the total number of members (25) and solve for y.
38-y = 25
-y = 25-38
-y = -13
y = 13 people own both a bike and a surfboard.
22-y = 22-13 = 9 people own just a bike only.
14-y = 14-13 = 1 person owns just a surfboard only.
As a check, 9+13+1+2 = 25, so the answer is confirmed.