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:

\( \frac{3!}{2!} \)
\( \frac{3 \times 2 \times 1}{2 \times 1} \)
\( \frac{3}{1} \)
3

Average speed in miles per hour is the number of miles traveled divided by the number of hours:

Solving for distance:

distance = \( \text{speed} \times \text{time} \)
distance = \( 20mph \times 1h \)
20 miles

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

4 + (3 + 2) ÷ 3 x 3 - 5²
P: 4 + (5) ÷ 3 x 3 - 5²
E: 4 + 5 ÷ 3 x 3 - 25
MD: 4 + \( \frac{5}{3} \) x 3 - 25
MD: 4 + \( \frac{15}{3} \) - 25
AS: \( \frac{12}{3} \) + \( \frac{15}{3} \) - 25
AS: \( \frac{27}{3} \) - 25
AS: \( \frac{27 - 75}{3} \)
\( \frac{-48}{3} \)
-16

The equation for this sequence is:

a_n = a_n-1 + 2(n - 1)

where n is the term's order in the sequence, a_n is the value of the term, and a_n-1 is the value of the term before a_n. This makes the next number:

a₆ = a₅ + 2(6 - 1)
a₆ = 21 + 2(5)
a₆ = 31

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:

5x² - 9x²
(5 - 9)x²
-4x²