a man sells a radio set for rupees 605 and gains 10% at what price should he sell another lady of the same kind in order to gain 16%

638 rupees

Step-by-step explanation:

The radio cost him x.

He sold it at a 10% profit for for x + 10% of x which is the same as 1.1x

1.1x = 605

x = 605/1.1 = 550 rupees

It cost him 550 rupees.

To gain a 16% profit, he must sell it for 550 rupees + 16% of 550 rupees

That is the same as 116% of 550 rupees or 1.16 * 550 rupees

1.16 * 550 rupees = 638 rupees

638 rupees

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: