A dealer bought some toys for ₹1800. He sold 40% of these at a loss of 15% and $33\frac{1}{3}$ %of the remaining toys at 20% profit. At what percent profit should he sell the remaining toys to earn an overall profit of 10%? 

30%

Let the total quantity = 100

40% of this sold at 15% loss means, the selling price of 40% of 100= \(\frac{40 × 85}{100}\) = 34

Now remaining = 100 - 40 = 60

33.33% of this is sold at 20% profit , so the selling price = \(\frac{60 × 6}{5 × 3}\) = 24

Overall profit = 10% 

So overall selling price = 110% of 100 = 110

So, remaining must be sold at = 110 - 24 - 34 = 52 for 40.

Required profit percentage = \(\frac{(52 - 40) × 100}{40}\) = 30%