After an 8% discount from the list price,the sale price of a key chain was $18.40. What was the list price of the key chain

Solution:

L-list price
S-sale price
D-discount 
D-8% of L so 
 

The sale price is how much it costs after the discount:

 

Now we substitute in the known values and solve for L:

 

so L=$20.00