First, you need to know what "m" and "b" represents.
"m" represents slope, and "b" represents the y intercept.
For the equation you can combine the information to get y = mx + b
To find "m" indentify points, and see how many you have to go up/down then left/right.
To find "b" since the graphis given see where the line crosses the y axis. (0, b)
1. m = -1, b = 3
y = -1x + 3
2. m = 1, b = -3
y = 1x -3
3. m = 3/1 or 3, b = 1
y = 3x + 1
4. m = -3/1 or -3, b = -3
y = -3x -3
