Answer:
Ratio defined as the relative sizes of two or more values.
i.,e

As per the statement:
on every three hamburgers that McDonald's makes they use 9 pickles.
Unit rate per burger =

Then the ratio in the simplest form is: 3 : 1
We have to find how much will they use on a 100 burgers.
By definition of unit rate:

then;
= 300
Therefore, 300 pickles will they use on a hundred burgers.