Does anyone know how to do this

Angela is buying a dress that is on sale for 20% off. if the original price of the dress is $40.00, how much money is angela saving on the dress? a. $0.80 b. $3.20 c. $32.00 d. $8.00

An ant travels at a constant rate of 30cm every 2 minutes. at what speed does the ant travel per minute

Find the percent error of the measurement 4 cm