The equations a = n, b = 2n + 6 and c = n² - 1 are polynomials, and the expression for ab - c is n² + 6n + 1
<h3>How to determine the expression for ab - c?</h3>
The polynomials are given as:
a = n
b = 2n + 6
c = n² - 1
The expression ab - c is calculated using:
ab - c = n * (2n + 6) - (n² - 1)
Expand
ab - c = 2n² + 6n - n² + 1
Collect like terms
ab - c = 2n² - n² + 6n + 1
Evaluate
ab - c = n² + 6n + 1
Hence, the expression for ab - c is n² + 6n + 1
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ANSWER
80%
EXPLANATION
Donovan got 20 questions correct and 5 questions incorrect.
This means that the total number of questions he attempted in the test is the sum of correct and incorrect questions:
Total = 20 + 5
Total = 25
To find the percentage of correct answers, we have to divide the number of correct answers by the total number of questions attempted and multiply by 100 (per cent).
That is:

That is the percentage of correct answers.
Answer:
Ray : Line NA, Line NB, Line AB
Vertex : Vertex N
Angle: Angle ANB
Parallel Lines: None
Coplanar Points: Points C, A, F, N, B
Collinear Points: Points A, N, B
Segment Addition Postulate: AN + NB = AB
Perpendicular Lines: None