Which is the most reasonable interpretation of the slope of the trend line in the student model

I uploaded the answer to a file hosting. Here's link:

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step-by-step explanation:

i have done this all on a piece of paper but idk how to put it on here cuz it needs to be drawn

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: