5/8 of the remainder can be seen as :

Remainder = 8 units
5 of these units are sold in the afternoon.

What is left = 3 units

Now question says 1/4 of the computers are left. That's like saying 1 unit out of 4 units are left.

Since from above we know 3 units are left, we should change the numerator of the fraction ¼ to make it the same as 3.

We can do this by multiplying both numerator and denominator by 3

¼ = 3/12

So this means 3 units are left, out of the original 12 units.



So in the morning, number of units sold = 12 - 8 = 4

4 units = 32 computers
1 unit = 32 ÷ 4 = 8 computers

Total units sold = 12 - 3 = 9
9 units = 8 computers x 9 = 72 computers

So 72 computers are sold.