In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
final price = $316.00
discount = 20% = 20/100 = 0.2
Step 02:
original price:
final price = original price - original price * discount
final price = original price (1 - discount)
316 = original price ( 1 - 0.2)
316 = original price ( 0.8 )
316 / 0.8 = original price
395 = original price
The answer is:
The original price is $395