19) A TV is on sale for $1,600, which is a discount of 20%, what is the regular price?

Regular price = x

x - 0.2x = 1600

0.8x = 1600

you have to make "x" subject of formula by moving "0.8" to the other side. When you go to the other side, addition becomes subtraction, multiplication becomes division, and vice versa.

x = 1600/0.8 (0.8 was multiplication at the other end)

x = $2,000