Question 1: The y-intercept is where the line crosses the y-axis. The increments of the y-axis is by 20, and the y-intercept is at (0, 20).
The slope is the change in y over the change in x. Find two points:
(0, 20) and (2, 80)
Now:
(80 - 20)/(2 - 0) = 60/2 = 30
Slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept.
So:
y = 30x + 20
Question 2: Again, look for the y-intercept, which is pretty clear. It's (0, 60).
Now find two points:
(0, 60) and (2, 40)
Find the slope:
(40 - 60)/(2 - 0) = -20/2 = -10
So, the equation is:
y = -10x + 60
And, there you go!
