To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

-6c² - 8c²
(-6 - 8)c²
-14c²

To convert a negative exponent to a positive exponent, calculate the positive exponent then take the reciprocal.

1

A factorial is the product of an integer and all the positive integers below it. To solve a fraction featuring factorials, expand the factorials and cancel out like numbers:

\( \frac{6!}{5!} \)
\( \frac{6 \times 5 \times 4 \times 3 \times 2 \times 1}{5 \times 4 \times 3 \times 2 \times 1} \)
\( \frac{6}{1} \)
6

Monica scored 87% on the test meaning she earned 87% of the possible points on the test. There were 120 possible points on the test so she earned 120 x 0.87 = 104 points. Each question is worth 4 points so she got \( \frac{104}{4} \) = 26 questions right.