As Given ,
Members play football and basketball = 20
Members play football and vallyboll = 15
Members play basketball and volleyball = 26
Members play all games = x
Members play only one game = 2x
There are total number of members = 110
From above data we can write,
110 = 20 + 15 + 26 + x + 2x + 2x + 2x
110 = 61 + 7x
7x = 110 - 61
7x = 49
x = 7members
To find,
Member play basketboll altogether
= 20 + 26 + 2x + x
We know that x = 7,
= 20 + 26 + 14 + 7
= 67 members