When given a graph or table, you first want to figure out the slope. Look at the graph or table, and see how much does y change when x change in a certain amount? You want it as a rise/run so if x increases 2 when y increases 3 then the slope would be 3/2.
Next, you want to find the y intercept.
Look at the y value when x is 0. If the y is -2 when x=0, then b=-2.
When given its graph, find a y value when x is 0. If the y is 4 when x=0 then b=4
