Selling price of the chair = 1440 rupees
Percentage of loss made by the shopkeeper = 10%
Let us assume the price at which the shopkeeper bought the chair = x
Then
90% * x = 1440 rupees
(90/100) * x = 1440 rupees
9x/10 = 1440 rupees
9x = 1440 * 10 rupees
9x = 14400 rupees
x = 14400/9 rupees
= 1600 rupees
So the price at which the shopkeeper bought the chair was 1600 rupees. I hope the procedure is clear enough for you to inderstand.