1)
Let the total number of students be X
students liking football = { 1 - (2/5 + 2/7) } * X
= { 1 - (24/35) } * X
= { 11/35 } * X
= 11X / 35
Given that, the number of students liking football is 11
So, 11X / 35 = 11
11X = 11 * 35
X = 11 * 35 / 11
X = 35
ie, Total number of students = 35
Students liking cricket = 2/5 * 35
= 14
2)
Let the number be X
So, 2 (X + 6) = 3X - 4
2X + 12 = 3X - 4
3X - 4 = 2X + 12
3X - 2X = 12 + 4
X = 16