In order to find how many additional workers are needed to staff the extra crews you first need to calculate how many workers are on a crew. There are 10 workers at the company now and that's enough to staff 5 crews so there are \( \frac{10}{5} \) = 2 workers on a crew. 10 crews are needed for the busy season which, at 2 workers per crew, means that the roofing company will need 10 x 2 = 20 total workers to staff the crews during the busy season. The company already employs 10 workers so they need to add 20 - 10 = 10 new staff for the busy season.

There are 4 3-passenger taxis available so that's 4 x 3 = 12 total seats. There are 15 people needing transportation leaving 15 - 12 = 3 who will have to find other transportation.

The absolute value is the positive magnitude of a particular number or variable and is indicated by two vertical lines: \(\left|-5\right| = 5\). In the case of a variable absolute value (\(\left|a\right| = 5\)) the value of a can be either positive or negative (a = -5 or a = 5).

A rational number (or fraction) is represented as a ratio between two integers, a and b, and has the form \({a \over b}\) where a is the numerator and b is the denominator. An improper fraction (\({5 \over 3} \)) has a numerator with a greater absolute value than the denominator and can be converted into a mixed number (\(1 {2 \over 3} \)) which has a whole number part and a fractional part.

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

9\( \sqrt{18} \) - 9\( \sqrt{2} \)
9\( \sqrt{9 \times 2} \) - 9\( \sqrt{2} \)
9\( \sqrt{3^2 \times 2} \) - 9\( \sqrt{2} \)
(9)(3)\( \sqrt{2} \) - 9\( \sqrt{2} \)
27\( \sqrt{2} \) - 9\( \sqrt{2} \)

Now that the radicands are identical, you can subtract them: