To simplify a radical, factor out the perfect squares:

\( \sqrt{28} \)
\( \sqrt{4 \times 7} \)
\( \sqrt{2^2 \times 7} \)
2\( \sqrt{7} \)

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

2 + (4 + 2) ÷ 2 x 2 - 3²
P: 2 + (6) ÷ 2 x 2 - 3²
E: 2 + 6 ÷ 2 x 2 - 9
MD: 2 + \( \frac{6}{2} \) x 2 - 9
MD: 2 + \( \frac{12}{2} \) - 9
AS: \( \frac{4}{2} \) + \( \frac{12}{2} \) - 9
AS: \( \frac{16}{2} \) - 9
AS: \( \frac{16 - 18}{2} \)
\( \frac{-2}{2} \)
-1

The factors of a number are all positive integers that divide evenly into the number. The factors of 20 are 1, 2, 4, 5, 10, 20.

To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 2 are [2, 4, 6, 8, 10, 12, 14, 16, 18, 20] and the first few multiples of 6 are [6, 12, 18, 24, 30, 36, 42, 48, 54, 60]. The first few multiples they share are [6, 12, 18, 24, 30] making 6 the smallest multiple 2 and 6 share.

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

\( \frac{2 x 3}{2 x 3} \) - \( \frac{4 x 1}{6 x 1} \)

\( \frac{6}{6} \) - \( \frac{4}{6} \)

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

\( \frac{6 - 4}{6} \) = \( \frac{2}{6} \) = \(\frac{1}{3}\)

To multiply terms with radicals, multiply the coefficients and radicands separately:

4\( \sqrt{6} \) x 5\( \sqrt{3} \)
(4 x 5)\( \sqrt{6 \times 3} \)
20\( \sqrt{18} \)

Now we need to simplify the radical:

20\( \sqrt{18} \)
20\( \sqrt{2 \times 9} \)
20\( \sqrt{2 \times 3^2} \)
(20)(3)\( \sqrt{2} \)
60\( \sqrt{2} \)