A shop keeper sold two toys for Rs. 990 each. On first toy he gained 10% and on the second he lost 10%. Find the total percentage gain or loss.

Correct option is B

Given:
Selling price of two toys Rs. 990 each
Increase / Decrease % = 10%
Formula used:
Loss % = $$\frac{CP - SP}{CP}\times 100$$​​
SP(selling price) = Cost Price(CP)×(100 + Profit%)/100
SP = CP(100 - loss%)/100

Solution:

Total Selling Price = SP of first toy + SP of second toy

990+990=1980

CP of the first toy he gained 10%

990 × 100/(100 + 10)

= Rs. 900

CP of the second toy he loss 10%

990 × (100)/(100 - 10)

= Rs. 1100

Total Cost Price = CP of first toy + CP of second toy

900 + 1100 = Rs. 2000

Total Selling Price = SP of first toy + SP of second toy

990 + 990 = Rs. 1980

Loss% = (2000 - 1980)× 100/2000 =1%

Loss percent = 1%