First, set up a porportion to help you answer the question. Put percent paid/100 is equal to sale price/ original. The percent paid would be 75% because if the chair is 25% OFF then you would pay 75%. So then you would define your variable (I'll use x). X equals the original price. So, 75/100 equals 90/x. Then you can reduce 75/100 to 3/4 and cross multiply to get 3x=360. Then you would divide both sides by 3 to get x=120. So the original price of the chair was $120