A number, on subtracting 15 from it reduces to its 80%. What is 40% of the number ?

Answer: Option C

Let the number = x
According to the question,
x - 15 = $$\frac{80x}{100}$$
x - 15 = $$\frac{4x}{5}$$
5x - 75 = 4x
x = 75
Required answer
= 75 × $$\frac{40}{100}$$
= 30