2/5 of a set of notebooks are sold on the first day. 3/4 of the remaining got sold on the second day. If 75 notebooks remain still, how many notebooks were kept for sale?

Correct option is D

Given:

2/5 of a set of notebooks are sold on the first day.

3/4 of the remaining got sold on the second day.

Solution:

Let the total number of notebooks kept for sale = x .

On the first day, 2/5 of the notebooks are sold, so the remaining notebooks after the first day are:

Remaining after 1st day = $$x - \frac{2}{5}x = \frac{3}{5}x$$​​

On the second day, 3/4 of the remaining notebooks are sold, so the remaining notebooks after the second day are:

Remaining after 2nd day} = $$\frac{3}{5}x - \frac{3}{4} \times \frac{3}{5}x = \frac{3}{20}x$$​​

We are given that 75 notebooks remain after both days. Therefore, we can set up the equation:

$$\frac{3}{20}x$$​ = 75

Solving for x :

x =$$\frac{75 \times 20}{3}$$​ = 500

Thus, the total number of notebooks kept for sale was 500.