Question

by selling a watch for 1440.a man loses 10% at what price should he sell it to gain 10%

Answer 1

s.p of watch at 10% loss =1440
loss%=10%
now cp be x 
then
s.p.=cp-10%*cp
or,1440=x-(10/100)x
or,1440=90x/100
OR,x=1600
now from second condition
profit%-=10%
cp=1600
now
sp=cp+10%*cp
    =1600+10%*1600
    =1760

Answer 2

Find the cost price of the watch:

Loss = 10%

Selling Price = 100 - 10 = 90%

Selling Price = Rs 1440

90% = 1440

1% = 1440 ÷ 90  = 16

100% = 16 x 100 = Rs 1600

Find the selling Price:

Profit = 10%

Profit = 10% of Rs 1600 = 0.1 x 1600 = Rs 160

Selling Price = Cost Price + Profit

Selling Price = 1600+ 160 = Rs 1760

Answer: He should sell it at Rs 1760