By selling 130 cassettes, a man gains an amount equal to the selling price of 5 cassettes. Find the gain per cent.
Let × be the price of a cassette.
Selling Price of 5 cassettes = 5x.
Selling Price of 130 cassettes = 130x.
Cost Price of 130 cassettes = 130 × – 5x
= 125x
Gain = SP - CP
= 130 × – 125x
= 5x
= 4%
10