The distributive property for division helps in solving expressions like \({b + c \over a}\). It specifies that the result of dividing a fraction with multiple terms in the numerator and one term in the denominator can be obtained by dividing each term individually and then totaling the results: \({b + c \over a} = {b \over a} + {c \over a}\). For example, \({a^3 + 6a^2 \over a^2} = {a^3 \over a^2} + {6a^2 \over a^2} = a + 6\).

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 16 workers at the company now and that's enough to staff 4 crews so there are \( \frac{16}{4} \) = 4 workers on a crew. 9 crews are needed for the busy season which, at 4 workers per crew, means that the roofing company will need 9 x 4 = 36 total workers to staff the crews during the busy season. The company already employs 16 workers so they need to add 36 - 16 = 20 new staff for the busy season.

To fill a 8 gallon tank exactly halfway you'll need 4 gallons of fuel. Each fuel can holds 2 gallons so:

cans = \( \frac{4 \text{ gallons}}{2 \text{ gallons}} \) = 2

The greatest common factor (GCF) is the greatest factor that divides two integers.

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

\( \frac{12 + 6 + 11 + 7}{4} \) = \( \frac{36}{4} \) = 9