If Ram sold an article at 4/5 of its actual selling price, he would have incurred a loss of a 40%. Find his actual profit/Loss %?

Suppose that the Actual S.P. of an article is 100 Rs. So Ram would've sold the article @ 80 Rs. Now the loss incurred is 40%. So we can say that (CP-SP)/SP = 4/10. Putting SP as 80 in this equation we get CP =112. Now we can calculate the actual loss by putting CP and SP in the following equation :
Loss = (CP-SP)*100/CP, which will be 28.57%.

Let Actual SP be 100 =>New SP = 80
40% loss i.e. 60% CP => 0.6CP = 80 thus CP = (400/3)
Actual loss= ((CP-Actual SP)/CP) * 100 i.e. 25%

OR
40% loss i.e. 60% CP or (3/5)CP
(4/5)SP = (3/5)CP => SP=(3/4)CP => 25% loss

Actual SP= Rs 100.
New SP= Rs 80
Loss% = (Loss/CP)*100
so, 40 = [(CP-new SP)/CP] *100
40 = [(CP-80)/CP)*100
simplifying: 3/5 = 80/CP
CP = 400/3

Now, CP > SP, so LOSS.

LOSS % = [(400/3 - 100) ]/ [400/3] * 100 = 25%