You have to insert the passage first
In this case, the vector is passing through a right angle as shown with the little square on the left side. (all right angles equal 90 degrees) so you would simply subtract 64 from 90. (90 - 64 = 26) so x equals 26 degrees.
I am not sure about the last two phrases, but here's what I think.
2(n+18)
18(2+n)
