Profit on selling 10 candles equals selling price of 3 bulbs. While loss on selling 10 bulbs equal selling price of 4 candles. Also profit percentage equals to loss percentage and cost of a candle is half of cost of a bulb. What is ratio of selling price of candles to selling price of a bulb?

Candle - - - - - - - - Bulb
CP . . . . A - - - - - - - - B
SP . . . . C - - - - - - - - D
$$\eqalign{ & and.\,C = 2A \cr & {\text{Profit}} = 10\left( {B - A} \right) = 3D \cr & {\text{Loss}} = 10\left( {C - D} \right) = 4B \cr & {\text{Profit}}\% = \frac{{ {3D \times 100} }}{{10A}} \cr & {\text{Loss}}\% = \frac{{ {4B \times 100} }}{{10C}} \cr & {\text{Now,}}\,{\text{By}}\,{\text{the}}\,{\text{questions}}, \cr & \frac{{ {3D \times 100} }}{{10A}} = \frac{{ {4B \times 100} }}{{10C}} \cr & \frac{B}{D} = \frac{3}{2} = 3:2 \cr} $$