If goods be purchased for Rs.540 and one third sold at a loss of 20%. At what gain percent should the remainder be sold so as to gain 10% on the whole transaction ?

25%

In this type of questions we do not need actual given amount so,

Let total = 90

After one third sold at a loss of 20% remaining  = 30 × \(\frac{4}{5}\) = 24

Total selling price should be 99 ( 110% of 90 )

Now two third has to be sold at = 99 - 24 = 75

Profit at which remaining has to be sold at = 75 - 60 = 15

= 15 × \(\frac{100}{60}\) = 25%