CD = x
BC = y
AB = 85
BD = BC+CD = y+x
tan(angle) = opposite/adjacent
tan(28) = BC/AB
tan(28) = y/85
85*tan(28) = y
y = 85*tan(28)
y = 45.1953016912257
tan(angle) = opposite/adjacent
tan(31) = BD/AB
tan(31) = (y+x)/85
tan(31) = (45.1953016912257+x)/85
85*tan(31) = 45.1953016912257+x
51.0731526173427 = 45.1953016912257+x
51.0731526173427-45.1953016912257 = 45.1953016912257+x-45.1953016912257
5.877850926117 = x
x = 5.877850926117
So CD is roughly 5.877850926117 meters
The difference between set of whole numbers and a set of integers is that:
Whole numbers = {0, 1, 2, 3, 4, 5...}
Integers = {..., -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5...}
If we name contents of the first set as n, in the second set you can have 2n-1 numbers (because we count 0 only once in both sets).
The question is worded a bit strangely (in my opinion anyway), but I think your teacher wants you to describe how exponents work.
Let's say we had the expression 
The base is 5 as its the bottom most value (think of something like the base of a tree or building). The exponent is 3.
The exponent of 3 tells the reader to multiply the base 5 by itself 3 times like so

With larger exponents, it becomes more tedious to write out all the repeated multiplications, which is why many calculators have an exponent button to save time.
There are 12 inches in one foot. 120 x 12 = 1,440 inches. The correct ratio to be placed is the 5th one (aka 12 inches over 1 foot).
Answer:
34, 20, 35, ...
Step-by-step explanation:
From what I see, it is alternating between two patterns: +5 starting at 5, and +1 starting at 31.