Plzs answer this fast

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

What is the slope of the line shown below?

Can some one explain how to slove specifically, what is the value of x? 0.9(x+1.4)-2.3+0.1x=1.6 enter the answer as a decimal in the box. x= ?