A dealer bought some toys for Rs.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%

A dealer wants to earn 10% profit on all toys

Assume A dealer has 10 toys and Cost is Rs. 1 for each.

Now 

1st ⇒ 10 × 40% = 4 toys

2nd ⇒ Remaining × 33\(\frac{1}{3}\)% = 6 × \(\frac{1}{3}\) = 2 toys

3rd ⇒ Rest toys = 10 - 4 -2 = 4

ATQ,

4 × (-15)% + 2 × (+20%) + 4 × (+x%) = 10 × 10%

-60% + 40% + 4x% = 100%

                       4x% = 120%

                         x = 30