The original price was $225 and the price after the discount was $180, what was the discount percent

The discount percent is 20% off because you would subtract the discount from the original price and get 45. 45 is 20% of 225.

To find the answer, you have to make a proportion. 
Percent of discount = discount / regular price 
d = 45 / 225 
d =0.2
So to covert 0.2 to a percent, move the decimal point 2 places to the right.
= 20%
( By the way, 45 is $225 - $180)
To check it, I'm gonna multiply $225 * 0.20 = 45
And then subtract 225 - 45 = 180 
So the discount percent is 20%