Let xx be the original price. The original price minus the discount is the sale price so we write:

x−0.25x=15.75

Solve for x:

0.75x=15.75

\(\displaystyle{x}=\frac{{15.75}}{{0.75}}\)

x=21

So, the original price of the shirt is $21.

x−0.25x=15.75

Solve for x:

0.75x=15.75

\(\displaystyle{x}=\frac{{15.75}}{{0.75}}\)

x=21

So, the original price of the shirt is $21.