Answer:
$12.50
Explanation:
Equation: original(1-x%)=new
original(1-20%)=10
We can make the original price x since that is what we are trying to find.
x(1-20%)=10
x-20%x=10
20%=1/5
4/5x=10
multiple by 5/4 to leave x alone
x=5/4*10
x=12.5
So the original price was $12.50