The answer is s = -3/2e + 17.
e - the number of ounces of the entree
s - the number of ounces of the side dish
Entree has 45 calories per ounce: E = 45e
Side dish has 30 calories per ounce: S = 30s
Meal is total 510 calories: x = 510
Meal consists of the entree and the side dish:
x = E + S
Now, just substitute:
510 = 45e + 30s
Now, to find theĀ function that relates the number of ounces of the side dish that he eats to the number of ounces of the entree that he eats, just solve for s:
510 = 45e + 30s
30s = 510 - 45e
s = (510 - 45e)/30
s = 510/30 - 45e/30
s = 17 - 3/2e
This is the same as:
s = -3/2e + 17