When 125 is subtracted from a number, it reduces to its 37.5 percent. What is 25 percent of that number ?

Answer: Option A

Let the number be x
Then,
$$\begin{array}{rl}& \Rightarrow x=125=37\frac{1}{2}\%\text{ of }x\\ & \Rightarrow x-125=\frac{75}{2}\times \frac{1}{100}\times x\\ & \Rightarrow x-125=\frac{3x}{8}\\ & \Rightarrow x-\frac{3x}{8}=125\\ & \Rightarrow \frac{5x}{8}=125\\ & \Rightarrow x=\left(\frac{125\times 8}{5}\right)\\ & \Rightarrow x=200\\ & \therefore 25\%\text{ of 200}\\ & =\left(\frac{25}{100}\times 200\right)\\ & =50\end{array}$$