32 is 40 percent of what number?
A. 12.8
B. 128
C. 80
D. 800

Hint: Assume the required number to be an unknown quantity x. Now, formulate an equation on the basis of the given condition. Then solve for the unknown quantity from the obtained equation.

Complete step-by-step answer:
Let us assume the number whose 40 percent is 32 to be x.
Then on the basis of the given condition, we obtain the equation as,
$\dfrac{40}{100}\cdot x\text{ = 32 }....\text{(i)}$
Hence, we solve the equation (i) and get the required solution.
$\begin{align}
  & \dfrac{40}{100}\cdot x\text{ = 32} \\
 & \Rightarrow \text{ }x\text{ = 32 x }\dfrac{100}{40} \\
 & \therefore \text{ }x\text{ = }\dfrac{32\text{ x 10}}{4}\text{ = 8 x 10} \\
 & \text{ = 80} \\
\end{align}$
Hence, we obtain the value of the unknown quantity to be 80.
Thus, 32 is 40 percent of the number 80. So, the correct answer is option C.

Note: One has to keep in mind the question is asking 32 is 40 percent of which number. A common mistake is to think that we are being asked to find the 40 percent of 32. In that case, the answer will be,
$\dfrac{40}{100}\text{ x 32 = 4 x 3}\text{.2 = 12}\text{.8 }$
Now, 12.8 is also an option in the given question. So, there is a chance that one thinks to get the right answer even if it is actually wrong. Thus, the correct answer is option C, not option A.