Answer:
Ok, there are multiple ways of model this, one of the ways can be:
Knowing that a hornworm can strip a tomato plant of its foliage in about two days, we can count the number of hornworms (x, the input) and find the number of plants (y, the output) that they can eat in a day.
So, if a hornworm can eat a plant in two days, then in one day the worm can eat half a plant.
Then:
y = (0.5plants/worm)*x
This says:
The number of plants eaten in one day (y) is equal to half of the number of hornworms
OF course, there are a lot of other ways to model this, for example we can use the time as a variable x, and the number of plants as y.
Knowing that a worm eats a plant in two days:
y = (0.5 plants/day)*x
Now x is the number of days, and y is the number of plants that can be eaten by a single worm