The price of a sofa went down by 20%. The new reduced price is $400. a. Complete the percent table and explain why the blank will be the price of the sofa before the reduction. 80% S $400 100% S _____ Where does the 80% come from, and why does it correspond to $400? b. Explain why you can't calculate the price of the sofa before the reduction by increasing $400 by 20%