In this table, x represents the pounds of peanuts purchased and y represents the cost, in dollars, for purchasing that amount of peanuts. Which equation represents this situation?

y = 2.5x

y = x + 2.5

y=x÷2.5

y=x−2.5

x y

1 $2.50

2 $5.00

3 $7.50

4 $10.00