profit and loss

Question

If a shopkeeper sells a shirt for $7 more, his profit increases from 12% to 17%. what's the cost of the shirt to the shopkeeper?

Answer 1

the profit is 12% of the cost

let p=profit, c=cost

p=12%*c

p=0.12c

p+7=17%*c

p+7=0.17c

p=0.12c

substitute

0.12c+7=0.17c

7=0.05c

700=5c

c=$140 is the cost of the shirt

12%*140=$16.80 for a profit

$140+$16.80=$156.80 is what he sells the shirt for to make a 12% profit

he sells the shirt for $7.00 more, or $156.80+$7.00=$163.80 and makes a profit of 17%

check:  $163.80-$140=$23.80 is the profit

$23.80/$140=17% ???

238/1400=119/700=17/100=17%, or

17%*$140=0.17*$140=$23.80, the new profit