What expression can be used to calculate the rate per minute at which the air freshener dispenses sprays?

You didn't give any answers, but, I hope this will help you out a bit:

for example, if the air freshener sprays 3 times every 20 minutes,

here are our points:

(20,3), (40,6), (60,9), (80,12)

lets take the second and third point to find the slope.

3/40 would be the slope.

3x + 4y -25 =0 represents the amount of change sianna should recieve

its totaly b

your welcome btw