Donald is participating in a fun run to raise money for the West Side Children's Hospital. The run is held at Donald's high school track. The more laps Donald runs around the track, the more money he raises for the hospital. There is a proportional relationship between the number of laps Donald runs, x, and the amount of money he raises for the hospital (in dollars), y.
x (laps) y (dollars)
1 $5
2 $10
3 $15
4 $20
Write an equation for the relationship between x and y. Simplify any fractions.
y=