To convert a negative exponent to a positive exponent, calculate the positive exponent then take the reciprocal.

The ratio of football cards to baseball cards is 7:2 and the ratio of baseball cards to basketball cards is 7:1. To solve this problem, we need the baseball card side of each ratio to be equal so we need to rewrite the ratios in terms of a common number of baseball cards. (Think of this like finding the common denominator when adding fractions.) The ratio of football to baseball cards can also be written as 49:14 and the ratio of baseball cards to basketball cards as 14:2. So, the ratio of football cards to basketball cards is football:baseball, baseball:basketball or 49:14, 14:2 which reduces to 49:2.

The equation for this sequence is:

a_n = a_n-1 + 2(n - 1)

where n is the term's order in the sequence, a_n is the value of the term, and a_n-1 is the value of the term before a_n. This makes the next number:

a₆ = a₅ + 2(6 - 1)
a₆ = 21 + 2(5)
a₆ = 31

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:

-8z⁵ - 2z⁵
(-8 - 2)z⁵
-10z⁵

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

vans = \( \frac{99}{12} \) = 8\(\frac{1}{4}\)

So, it will take 8 full vans and one partially full van to transport the entire team making a total of 9 vans.