Answer:
1. annual tuition 2. $-27139 3. slope = -0.91
Step-by-step explanation:
1. An independent variable is the factor that is not determined by the model in this case the annual tuition variable (the linear regression model factor)
2. substitute $30,000 into the linear regressions equation gives:
y = -0.91(30000) + 161 = -27139
This value tells us that when the annual tuition is $30,000 the average mid-career salary of graduates is predicted to be -$27,139
3. the slope if the regression is represented by the coefficient of the factor in the linear regression model. In this case, as the factor is x or the annual tuition, and the coefficient of this variable in the given example is -0.91 which in turn is the slope of the model.
I'll give you a hint. <u><em>You had to used pemdas stands for: p-parenthesis, e-exponents, m-multiply, d-divide, a-add, and s-subtracting.</em></u>
First you had to calculate with parenthesis first.

Then you add and subtract from left to right.

Final answer 
Hope this helps!
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-Charlie
The answer for this problem is x=12.