Question

Monthly incomes of two persons are in the ratio $5:4$ and their monthly expenditures are in the ratio of $9:7$. If each person saves Rs.$500$ per month, then what are their monthly incomes.

Answer 1

Let their monthly income be 5x,4x respectively.

Let their monthly expenditure be 9y,7y respectively.

$5x-9y=500$ ……….(1)

$4x-7y=500$ ………(2)

From (1) and (2)

$5x-9y=4x-7y$

$y=\frac{x}{2}$

From (1),

$5x-9\times \frac{x}{2}=500$

Or, $x=1000$

Their monthly income is 5000 and 4000 respectively.