Answer: C) Partial variation; $375
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Step-by-step explanation:
We don't have a direct variation because the initial cost isn't $0
The equation for this situation is y = 25x+375, where x is the number of yearbooks purchased and y is the total cost.
Notice how this line doesn't go through the origin. All direct variation graphs are straight lines through the origin.
So that's why we have partial variation instead.
The initial cost is simply the set up cost, aka the cost when x = 0. That initial cost is $375. The initial cost is located at the y intercept.
From that initial cost, we then add on multiples of $25 depending on how many yearbooks are purchased.
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In short, because the initial cost is $375, which is some nonzero value, this means we don't have direct variation. Instead, we have partial variation.