Question

the ratio of the income of two person is 9:7, and the ratio of their expenditure is 4:3.Each of them saves ₹200 yearly .find their yearly income.

Answer 1

Hey mate !
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Let the income of two persons be Rs 9x and Rs 7x and their expenditures be Rs 4y and Rs 3y respectively.

9x-4y = 2000  ...........(1)

7x-3y = 2000  ...........(2)

Multiply equation 1 by 3 and equation 2 by 4 to make the cofficients of y be equal .

Then we get ,

27x-12y = 6000  ........(3)

28x-12y =8000   .........(4)

Subtract Eq. (3) and Eq. (4) to eliminate y so that the cofficient of y is same.

So , we get

=> (28x-27x)-(12y-12y) = 8000-6000

=> x = 2000

Substituting this in equation (1), we get

=> 9(2000)-4y = 2000

=> y = 4000

Therefore monthly income of persons are
18000 and 14000 respectively .

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Hope it helps !