Given:
Let x be the number of tickets sold
Let y be the price of tickets sold
(0,0)(1,20)(2,40)(3,60)(4,80)
These points show that 1 ticket costs 20.
y = 20x
y = 20(0) = 0
y = 20(1) = 20
y = 20(2) = 40
y = 20(3) = 60
y = 20(4) = 80
The price of tickets sold is in direct variation to the number of tickets sold. This means that the increase in the number of tickets sold will correspond to an increase in the price of tickets sold at a constant rate of variation.