Explanation:
These linear equations are all straight lines, so if you find two points, you have the entire line. Any point (x,y) that satisfies the equation lies on the line. One approach to easily find two lines is to choose x=0, then find y and next, choose y=0 and find x.
For example, let's try that for x - 4y = 8:
assume x=0: -4y = 8 => y = -2, so (0,-2) is on the graph.
assume y=0: x = 8 so, (8,0) is on the graph.
Another approach to draw these graphs is to rework each equation to the form y = ax + b, where a will be the slope of the line, and b will be the intersection with the y axis.
There are lots of ways to go about this, find your preferred approach.