Question

A person gave $20\%$ of his income to his elder son, $30\%$ of the remaining to the younger son and $10\%$ of the balance he donated to a trust. He is left with Rs. $10,080.$ His income was

• A. Rs. $50,000$
• B. Rs. $40,000$
• C. Rs. $30,000$
• D. Rs. $20,000$

Answer 1

The correct option is D Rs. $20,000$

Let us assume he had Rs. $a$.

He gave $20\%$ of his income to his elder son.

Remaining Amount $=$ $\frac{80}{100}\times a=0.8a$

He gave $30\%$ of remaining to younger son.

Remaining Amount $=$ $0.7\times 0.8a$

Then he gave $10\%$ of the balance to a trust

Remaining income $=$ $0.9\times 0.7\times 0.8a$

$=0.504a$

Now it is given that final remaining amount $=$ $10800$

$\Rightarrow$ $0.504a=10800$

$\therefore$ $a=\frac{10800}{0.504}=$ Rs. $20,000.$