Question

PLEASE HELP ME FAST AND GIVE THE SOLUTION !!!

Answer 1

ravi'spocket money=5x
sanj.... =7x 
Ravi's exp...=3y
sanj........... =5y
5x-3y=80....(a)
7x-5y=80.....(b)
(a)*5 - (b)*3
25x-15y=400
21x-15y=240
x=40
ans=5x=5*40=200
7x=7*40=280

Original credits to Force1

Answer 2

Let Ravi pocket money =5x
Sanjeev pocket money =7x

Their expenditures are 3z,5z respectively.

Given,

5x -3z =80 ……(1)
7x -5z=80 …………(2)

Multiplying (1) by 5, (2) by 3

25x - 15z =400 ……(3)
21x-15z =240 …………(4)

subtracting (4) from (3)

25x - 15z =400 ……(3)
21x-15z =240 …………(4)
===================
4x =160

x =40.

now substituting 1 to get the value of y

5x -3z=80
5(40)-3z =80
200-80=3z
z =40=x.

Now,
Monthly pocket money of Ravi =5x =5(40)=200 Rs.
Monthly pocket money of Sanjeev =7x =7(40)=280 Rs.

Expenditure
1) Ravi = 3x =3(40)=120 Rs.
2) Sanjeev =5x = 5(40)=200 Rs.