I'm not sure how to find angle 5 and 6

angle 5 = 17 degrees

angle 6 = 129 degrees

Step-by-step explanation:

Start by finding angle 5 by doing 90+39+x+34=180

You get 17 degrees for angle 5

Then, find angle 6 by doing 17+34+x=180, which is 129 degrees.

a(n) = -20 + 5(n - 1)

Step-by-step explanation:

Each term is 5 more than the previous term:

-20, -15, -10, -5, 0, 5, ...

or

a(n) = -20 + 5(n - 1)