If the cost of $x$ metres of wire is $d$ rupees, then what is the cost of $y$ metres of wire at the same rate?
(a)$₹\left(\frac{x y}{d}\right)$
(b)₹ (xd)
(c)₹ (yd)
(d)$₹\left(\frac{y d}{x}\right)$
Answer
Answer (as printed): D
Explanation
Cost of $x$ metres $=₹ d$. Cost of 1 metre $=₹\left(\frac{d}{x}\right)$. Cost of $y$ metres $=₹\left(\frac{d}{x} \times y\right)=₹\left(\frac{y d}{x}\right)$.
Explanation as extracted from the printed page; notation may be imperfect.