
David W. answered 04/29/16
Tutor
4.7
(90)
Experienced Prof
"sell them at a 10% discount off the selling price and still make 20% profit on his cost"
That statement has two parts.
Let x = selling price
"still make 20% profit on his cost" relates to the cost of $90. It is:
cost + 20% of cost
1.20*cost [we can use 1.20 or 120/100 as needed in the problem]
1.20*$90
$108 [this is x, the selling price at which the retailer earns 20%]
Now, what is the marking price so the retailer can sell the jacket at 10% off the marked price [note word change]?
Let y = the price to be marked
marked price - 10% of marked price = $108
y - 0.1y = $108
0.9y = $108
y = $108/0.9 [divide both sides by 0.9]
y = $120
If the retailer marks a price of $120 on the jacket and sells it for 10% off (that is, $120-$12=$108), there will still be a 20% profit because the cost was only $90 (and $90 + 20% of $90 is $108).