Use a linear equation to represent and solve the following situation
a) marco received a gift card for a local coffee shop. every time he goes to the shop, he gets a medium coffee. after
two visits, the gift card had $19.70. after four visits, the gift card had $14.40.
a. how much does each medium coffee cost?
b. what was the original value on the gift card?
c. how many cups of medium coffee can marco buy using the gift card?