Question

income to expenditure ratio of a person is 9:7 his monthly income is Rs 9000 what is Saving per month

Answer 1

As
9x=9000
9x=9000
x=9000/9
1000


Expenditure=1000*7
=7000
Savings =9000-7000
=2000

Answer is 2000
Hope you will find that :-)

Answer 2

You can use ratios for this
let the expenditure be x
9 : 7 :: 9000 : x
Product of extremes = 9x
Product of means = 9000x7= 63000
9x = 63000
x = 63000/9 = 7000

Savings = Income - Expenditure
= 9000 - 7000
= 2000