What’s for 5 & 6? the image is next to them. pls help

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

Mariah is randomly choosing three books to read from the following: 5 mysteries, 7 biographies, and 8 science fiction novels. which of these statements are true? check all that apply. there are 20c3 possible ways to choose three books to read. there are 5c3 possible ways to choose three mysteries to read. there are 15c3 possible ways to choose three books that are not all mysteries. the probability that mariah will choose 3 mysteries can be expressed as . the probability that mariah will not choose all mysteries can be expressed as 1 −

Question 6(multiple choice worth 5 points) (05.02 lc) what is the value of x? a right angle is shown divided into two parts. the measure of one part of the right angle is 10 degrees. the measure of the other part is 2x 20 40 45 85