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:

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

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{13 + 7 + 14 + 6}{4} \) = \( \frac{40}{4} \) = 10

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

1b³ + 5b³
(1 + 5)b³
6b³

To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 9 are [9, 18, 27, 36, 45, 54, 63, 72, 81, 90] and the first few multiples of 15 are [15, 30, 45, 60, 75, 90]. The first few multiples they share are [45, 90] making 45 the smallest multiple 9 and 15 share.

Next, convert the fractions so each denominator equals the lowest common multiple:

\( \frac{2 x 5}{9 x 5} \) - \( \frac{7 x 3}{15 x 3} \)

\( \frac{10}{45} \) - \( \frac{21}{45} \)

Now, because the fractions share a common denominator, you can subtract them:

\( \frac{10 - 21}{45} \) = \( \frac{-11}{45} \) = -\(\frac{11}{45}\)

To multiply fractions, multiply the numerators together and then multiply the denominators together:

\( \frac{3}{8} \) x \( \frac{1}{6} \) = \( \frac{3 x 1}{8 x 6} \) = \( \frac{3}{48} \) = \(\frac{1}{16}\)