the trend line shows that in general the time student spends reading per week the time he or she spends watching television and vice versa​

Can someone explain the elimination method to me for this problem?

What is the slope of the line that contains the points (4,8) and (9,8)? what type of line is it?

Which of the following correctly justifies statement four of the two column proof? a. corresponding angles theorem b. transitive property of equality c. vertical angle theorem d. substitution property of equality