Question

if the price of a watch is increased by 15% the increase increase in price is 90 .what was the price of watch earlier

Answer 1

Let the actual amount as x 
Then ( 15 ) % of x = 90 
⇒  (15 / 100 ) x ( x ) = 90 
⇒  15 x = 90 x 100
⇒  x = 6 x100
⇒ x= 600

Answer 2

Let the price of watch = P
A/C to question,
if price of watch increases 15% , then increase in price = 90
15% of P = 90
15P/100 = 90
P = 90*100/15
P = 600

hence, price of watch = 600