The equation that she needs to use to make 125 servings is:
y = 125*(4 + 1/3 )cups = (125*4 + 125/3) cups.
We know that the recipe calls for 4 + 1/3 cups of pineapple juice per serving. So, if you want to make x servings, then you need to use the recipe x times, which means that you will need x*(4 +1/3) cups of pineapple juice.
In this case we know that Julie wants to make 125 servings, then we can evaluate the linear equation above in x = 125, we will get:
y = 125*(4 + 1/3 )cups = (125*4 + 125/3) cups.
If you want to learn more about linear equations:
https://brainly.com/question/1884491
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