Question

29. The monthly incomes of A and B are in the ratio 5:4 and their monthly
expenditures are in the ratio 7:5. If each saves 9000 per month, find
the monthly income of each.
​

Answer 1

Let monthly incomes be x

Let monthly expenditures be y.

ATQ,

5x-7y=9000. -(1)

4x-5y=9000. -(2).

Multiplying (1) by 4 and (2) by 5

20x-28y=36000

20x-25y=45000

(-). (+). (-)

0x-3y=-9000

y=3000-(3)

5x-7y=9000

Putting values from (3)

5x-7(3000)=9000

5x=9000+21000

5x=30000

x=30000/5

x=6000

Monthly income of A=5(6000)=30000

B=4(6000)=24000

Hope it helps!