Answer:
80$
Step-by-step explanation:
First set up an equation like this, where x is the original price:
x * 0.80 = 40
Because we know that 80 percent of the mystery number is 40, this works.
Then divide both sides by the 0.80 (remember it is 0.80 and not 80, because it is a percent value) to get:
x = 50
