From the salary of an officer, 10\% is deducted as house rent, 20\% of the rest, he spends on conveyance, 20\% of the rest he pays as income tax and 10\% of the balance, he spends on clothes. Then, he is left with ₹ 15,552. Find his total salary.
(a)₹ 25,000
(b)₹ 30,000
(c)₹ 35,000
(d)₹ 40,000
Answer
Answer (as printed): B
Explanation
Let the total salary be ₹ $x$. Then, $(100-10) \%$ of (100-20)\% of (100-20)\% of (100 - 10)\% of $x=15552$ $$\begin{aligned} & \Leftrightarrow\left(\frac{90}{100} \times \frac{80}{100} \times \frac{80}{100} \times \frac{90}{100} \times x\right)=15552 \\ & \Leftrightarrow x=\left(\frac{15552 \times 10000}{64 \times 81}\right)=30000 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.