Kelly went to a store to purchase a coffee pot. She will use a coupon for 20% off. She can calculate the cost before sales tax using the follow expression, c represents the original cost of the coffee pot. C- 0.2c
Which other expression could kelly use to calculate her cost before sales tax?
A. 0.8c
B. 1.2c
C. 1.8c
D. 80c​