To simplify a radical, factor out the perfect squares:

\( \sqrt{20} \)
\( \sqrt{4 \times 5} \)
\( \sqrt{2^2 \times 5} \)
2\( \sqrt{5} \)

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:

5a³ - 7a³
(5 - 7)a³
-2a³

To add these radicals together their radicands must be the same:

4\( \sqrt{18} \) + 3\( \sqrt{2} \)
4\( \sqrt{9 \times 2} \) + 3\( \sqrt{2} \)
4\( \sqrt{3^2 \times 2} \) + 3\( \sqrt{2} \)
(4)(3)\( \sqrt{2} \) + 3\( \sqrt{2} \)
12\( \sqrt{2} \) + 3\( \sqrt{2} \)

Now that the radicands are identical, you can add them together:

The first few multiples of 2 are [2, 4, 6, 8, 10, 12, 14, 16, 18, 20] and the first few multiples of 8 are [8, 16, 24, 32, 40, 48, 56, 64, 72, 80]. The first few multiples they share are [8, 16, 24, 32, 40] making 8 the smallest multiple 2 and 8 have in common.

First, solve for \( \left|b + 5\right| \):

\( \left|b + 5\right| \) - 3 = 4
\( \left|b + 5\right| \) = 4 + 3
\( \left|b + 5\right| \) = 7

The value inside the absolute value brackets can be either positive or negative so (b + 5) must equal + 7 or -7 for \( \left|b + 5\right| \) to equal 7:

So, b = -12 or b = 2.