Apair of in-line skates is on sale for $90 if this price represents 9% discount form the original price, what is the original price to the nearest cent

Let x = original price in dollars

x is the original price
9% of this original price is equal to 0.09x

subtract: x - 0.09x = 0.91x

The discount price is equal to 0.91x and it's equal to 90 dollars, so they must be the same value. Ie.

0.91x = 90
0.91x/0.91 = 90/0.91
x = 98.9010989
x = 98.90

So the original price is $98.90