To add these fractions, first find the lowest common multiple of their denominators. The first few multiples of 5 are [5, 10, 15, 20, 25, 30, 35, 40, 45, 50] and the first few multiples of 7 are [7, 14, 21, 28, 35, 42, 49, 56, 63, 70]. The first few multiples they share are [35, 70] making 35 the smallest multiple 5 and 7 share.

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

\( \frac{4 x 7}{5 x 7} \) + \( \frac{8 x 5}{7 x 5} \)

\( \frac{28}{35} \) + \( \frac{40}{35} \)

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

\( \frac{28 + 40}{35} \) = \( \frac{68}{35} \) = 1\(\frac{33}{35}\)

To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 8 are [8, 16, 24, 32, 40, 48, 56, 64, 72, 80] and the first few multiples of 10 are [10, 20, 30, 40, 50, 60, 70, 80, 90]. The first few multiples they share are [40, 80] making 40 the smallest multiple 8 and 10 share.

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

\( \frac{4 x 5}{8 x 5} \) - \( \frac{8 x 4}{10 x 4} \)

\( \frac{20}{40} \) - \( \frac{32}{40} \)

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

\( \frac{20 - 32}{40} \) = \( \frac{-12}{40} \) = -\(\frac{3}{10}\)

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

\( \left|b + 2\right| \) - 1 = 0
\( \left|b + 2\right| \) = 0 + 1
\( \left|b + 2\right| \) = 1

The value inside the absolute value brackets can be either positive or negative so (b + 2) must equal + 1 or -1 for \( \left|b + 2\right| \) to equal 1:

So, b = -3 or b = -1.

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:

-4z² - 1z²
(-4 - 1)z²
-5z²

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

\( \frac{12 + 8 + 11 + 9}{4} \) = \( \frac{40}{4} \) = 10