Question

a boy after giving 1 by 4 of his money to one of his friends and 7 by 8 from the remainder to another has left 9 Rupees with him what was mount of money he was having at first

Answer 1

Remainder * 1/8 = 9        (As he gave away 7/8)
Remainder = 72
Remainder = 3/4 of original        (As he gave away 1/4)
3/4*Original = 72
Original = Rs. 96

Answer 2

Let the initial amount with the boy be S
So, ammount given by him to his first friend, A = S x (1/4)
Money remaining with the boy S' = S x (3/4)
Amount given to another friend, B = [S x (3/4)] x (7/8)
Money remaining with the boy S'' = [S x (3/4)] x (1/8)
But we know that this amount  S'' = 9
Equating both values of S'', we have;
S x (3/4) x (1/8) = 9
S x (3 / 32) = 9
S = 9 x (32 / 3)
S = 96
The boy had Rs. 96 initially.

I hope this is the answer.
Good luck, friend : )