Question

5. The ratio of the incomes of two persons is 9 : 7 and the ratio of their
expenditure is 4: 3. If each of them saves Rs. 200 per month, then their
monthly incomes.(a) Rs. 1,800, Rs. 1,400, (b) Rs. 1,600, Rs. 1,200,
(c) Rs. 1,400, Rs. 1,200,(d) None of these.

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Answer 1

Let their salaries be 9x and 7x

let their expenditure be 4y and 3y

so,

ATQ

9x-4y=200—(1)

7x-3y=200—(2)

so,

from (1)

x=(200+4y)/9—(3)

put x in (2)

7[(200+4y)/9]-3y=200

(1400+28y)/9-3y=200

(1400+28y-27y)/9=200

y+1400=1800

y=400

now put y in (3)

x=(200+4×400)/9

x=(200+1600)/9

x=1800/9

x=200

so,

salary of first person=9×200=1800 rs

salary of second person=7×200=1400 rs