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 have in common.

To divide fractions, invert the second fraction and then multiply:

\( \frac{4}{5} \) ÷ \( \frac{4}{8} \) = \( \frac{4}{5} \) x \( \frac{8}{4} \)

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

\( \frac{4}{5} \) x \( \frac{8}{4} \) = \( \frac{4 x 8}{5 x 4} \) = \( \frac{32}{20} \) = 1\(\frac{3}{5}\)

A number in scientific notation has the format 0.000 x 10^exponent. To convert to scientific notation, move the decimal point to the right or the left until the number is a decimal between 1 and 10. The exponent of the 10 is the number of places you moved the decimal point and is positive if you moved the decimal point to the left and negative if you moved it to the right:

0.0004258 in scientific notation is 4.258 x 10^-4

A factorial has the form n! and is the product of the integer (n) and all the positive integers below it. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.

First, solve for \( \left|b + 2\right| \):

\( \left|b + 2\right| \) - 7 = 8
\( \left|b + 2\right| \) = 8 + 7
\( \left|b + 2\right| \) = 15

The value inside the absolute value brackets can be either positive or negative so (b + 2) must equal + 15 or -15 for \( \left|b + 2\right| \) to equal 15:

So, b = -17 or b = 13.