The correct expressions are
-8.8
11(-2)
-6.7
We know that the trigonometric identity that uses the adjacent side and the hypotenuse is cosine. We can set this up as:

We need to solve for x, so let's isolate it:

So,
x = 10.2 units
An arithmetic sequence starts with one number and you add the common difference to the previous term to get the current term
So...
f(x)=mx+b
m=common difference
b=starting point
f(11)=125=11m+b
-
f(1)=5=1m+b
--------
120=10m
Divide both sides by 10
12=m
Your common difference is 12.