Question: The monthly income of A and B are in the ratio of 4 : 5 and their monthly expenses are in the ratio of 8 : 11. If each of them saves Rs. 1600 per month, then monthly income of B is
(a) Rs. 2500
(b) Rs. 6000
(c) Rs. 3500
(d) Rs. 4000

Ans: (b) Rs. 6000

Explanation:

Income = Expenditure + Savings

Hence, Income – Savings = Expenditure

Income of A : B = 4 : 5

Let, income A and B = 4x and 5x

Aliter

Income = 4x, 5x

Expenditure = 8y, 11y

We want to find out 5x = ?

ATQ, 4x – 8y = 5x – 11y = 1600

Now, 5x – 11y = 4x – 8y
\qquad \Rightarrow x = 3y

So, 4x – 8y = 1600
\Rightarrow 12y – 8y = 1600
\Rightarrow 4y = 1600
\Rightarrow y = 400

\therefore x = 3y = 1200
\Rightarrow 5x = 6000

Similar Question: The monthly income of P and Q are in the ratio of 5 : 6, and their monthly savings are in the ratio of 2 : 3. If each of them spend Rs. 1200 per month, savings of P is - (a) Rs. 800 (b) Rs. 1000 (c) Rs. 400 (d) Rs. 1800