Question

A shopkeeper sells two computers for Rs 24000 each. On first he gained 20% and on the other, he lost 20%. What is the overall gain or loss percentage?

Answer 1

Cost Price of Computers are 20000(the one on which he has profit) and 30000 (loss)
Total cost price=50000
Total selling price = 48000
$\therefore$ Loss percent = 4 %

Answer 2

Simple formula, if an item is sold at same price in both cases, and if there is x% loss in one case, while x% profit in the other, than overall, there is LOSS.

And, Loss% = (x/10)^2.

Therefore, here there is LOSS, and

Loss% = (20/10)^2 = 4%

Answer 3

sp1 = 24000

for the first comp. he gained 20% profit  which is equal to 1/5          
cp1     :        sp1

denominator: denominator+nominator
5         :       6

 5*4000=20000:6*4000=24000   
sp2 = 24000

for the first comp. he loss 20% which is equal to 1/5          
cp2     :        sp2

denominator: denominator-nominator
5         :       4

 5*6000=30000:4*6000=24000   
total cost price cp = cp1+cp2 = 20000+30000 = 50000

total selling price sp = sp1+sp2 = 24000+24000 = 48000

total loss = 50000-48000 = 2000

hence  cp     :     sp

        50000:48000

          25:24

1/25*100 = 4%

he got loss of 4% answer.