Question

the ratio of incomes of 2 persons is 11:7 and the ratio of their expenditures is 9:5. if each of them manages to save 400 rs per month then find their monthly incomes

Answer 1

let their income ratio be 11x and 7x
and their expenditure ratio be 9y and 5y

therefore 11x-9y=400. (I)
again a/q
7x-5y=400. (ii)
from I and ii
11x-9y=400. ×7
7x-5y=400. ×11

77x-63y=2800
77x-55y=4400
subtracting we get
-8y =-1600
y=200

therefore,
x=(400+1800)/11
=2200/11
=200
therefore,
income of first person =11×200
=2200
income of second person =7×200
=1400