
Kathleen O. answered 04/29/20
Editor/Researcher, Economics, Finance, Writing teacher, Ivy League
The information you need is clearly given in the problem since The equation of any straight line, called a linear equation: y = mx + b.
m is the slope of the line and b is the y-intercept.
The y-intercept of the line is the value of y at the point where the line crosses the y axis.
So, for example, in the first problem, you are given 9 as the y intercept and 1/2 as the slope. y = 1/2x + 9.
Take it from there! Best of luck.