We can solve problems where there is a percent increase or decrease by using what we know about equations. For example, a camping store increases the price of a tent by 25%. A customer then uses a $10 coupon for the tent and pays $152.50. We can draw a diagram that shows first the 25% increase and then the $10 coupon.

Three tape diagrams of unequal length. Top diagram, original price, one part labeled p. Middle diagram, labeled 25% increase, 4 equal parts which total to the same length as p above, with another equal part on the end labeled point 25 p. Third diagram, same total length as diagram above, labeled 10 dollar coupon, first part labeled 152 point 50, second part, dotted outline, labeled 10.

The price after the 25% increase is $p+0.25p$ or $1.25p$. An equation that represents the situation including the $10 off for the coupon is $1.25p-10=152.50$. To find the original price before the increase and discount, we can add 10 to each side and divide each side by 1.25, resulting in $p=130$. The original price of the tent was $130.