Martin has a gift card to a coffee shop. Each day he buys the same coffee. This table shows the amount remaining in dollars on the gift card on different days. Time (days) 2 4 5 7 Amount remaining ($)

Martin has a gift card to a coffee shop. Each day he buys the same coffee. This table shows the amount remaining in dollars on the gift card on different days. Time (days) 2 4 5 7 Amount remaining ($) $24.10 $18.20 $15.25 $9.35 Which equation represents this situation, where x is the time and y is the amount remaining?