If goods be purchased for ₹450 and one third sold at a loss of 10%. At what gain percent should the remainder be sold so as to gain 20% on the whole transaction ?

35%

Let Total C.P. is Rs. 30/-

C.P. of one part out of 3 is = Rs.10/-

1st is sold at 10% loss, therefore loss is = Rs.1

To gain 20% on whole part, S.P. should be = 30 × 120% =Rs.36

Profit = 36 - 30 = Rs.6/-

1st has been sold at a loss of Rs.1/- ,

Therefore, Rs.7 profit is required on remaining 2 parts to make 20% overall.

Hence,

Profit % should be = \(\frac{7}{20}\) × 100 = 35%