Given
The pocket money of Ravi and Sanjeev are in the ratio 5: 7
So, we can assume the pocket money of Ravi as 5k and that of Sanjeev as 7k.
Also, give that
The expenditure of Ravi and Snajeev are in the ratio 3: 5
So, it can be taken as the expenditure of Ravi as 3m and that of Sanjeev as 5m.
And, each of them saves Rs 80
This can be expressed as below:
5k – 3m = 80 ….. (a)
7k – 5m = 80 …… (b)
Solving equations (a) and (b), we have
k = 40 and m = 40
Therefore, the monthly pocket money of Ravi is Rs 5k = Rs 5 $$\times$$ 40 = Rs 200 and that of Sanjeev is Rs 7k = Rs 7 $$\times$$ 40 = Rs 280.