i believe the other person who answered is incorrect.
to find the answer, find what 20% of $5.00 is by dividing it by five (20% = 1/5). you find that the coupon will take $1.00 off of her purchase ($5.00/5 = $1.00). subtract the coupon amount from the original cost to get that she pays $4.00 of the original price, and saves $1.00.
