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:

-6x² - 9x²
(-6 - 9)x²
-15x²

The distributive property for multiplication helps in solving expressions like a(b + c). It specifies that the result of multiplying one number by the sum or difference of two numbers can be obtained by multiplying each number individually and then totaling the results: a(b + c) = ab + ac. For example, 4(10-5) = (4 x 10) - (4 x 5) = 40 - 20 = 20.

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

5\( \sqrt{7} \) x 9\( \sqrt{3} \)
(5 x 9)\( \sqrt{7 \times 3} \)
45\( \sqrt{21} \)

A factorial has the form n! and is the product of the integer (n) and all the positive integers below it. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.

Calculate the number of vans needed by dividing the number of people that need transported by the capacity of one van:

vans = \( \frac{39}{9} \) = 4\(\frac{1}{3}\)

So, it will take 4 full vans and one partially full van to transport the entire team making a total of 5 vans.