A student was asked to divide a number by $\frac{17}{8}$. Instead, he actually multiplied it by $\frac{17}{8}$ and hence got 225 more than the expected answer. What was the expected answer?
(a)64
(b)126
(c)136
(d)None of these
Answer
Answer (as printed): A
Explanation
Let the number be $x$. Then, $\frac{17}{8} x-\frac{8}{17} x=225 \Leftrightarrow \frac{289 x-64 x}{136}=225$ $$\Leftrightarrow \frac{225}{136} x=225 \Leftrightarrow x=136 . \therefore \quad \text { Expected answer }=136 \div \frac{17}{8}=\left(136 \times \frac{8}{17}\right)=64 .$$
Explanation as extracted from the printed page; notation may be imperfect.