Question

the ratio of incomes of two parents is 9:7 and the ratio of their expenditure is 4:3 . if each of them manages to save rs. 2000 per month , find their monthly income and expenditure .

frnds....
plz answer this question .....

Answer 1

Let the income be x and
the expenditure be y.
1st parents' monthly savings = 9x - 4y
2nd parents' monthly savings = 7x - 3y
But both of them saves ₹2000
9x - 4y = ₹2000 ...(1) × 3
7x - 3y = ₹2000 ...(2) × 4
Subtract (1) and (2)
27x - 12y = 6000
28x - 12y = 8000
- + -
_______________
x = 2000
_____________
Now putting the value of x in (1)
9 × 2000 - 4y = 2000
= 18000 - 4y = 2000
= -4y = - 16000
y = 4000
Monthly income of 1st parents = 9×2000 =18000 rs
Expenditure of 1st parents = 4 × 4000 = 8000 rs
Monthly income of 2nd parents = 7×2000 = 14000 rs
Expenditure of 2nd parents = 3 × 4000 = 12000rs