b is the Y-intercept or where the graph crosses the y-axis. they provide you with a few things which can help you figure this out. they give you the values of x and y in a table
X | Y
2 | -5
4 | -9 The difference between each Y value is 4...so, I add 4 to the -5
6 | -13 and get -1...going up another value for the X would be at 0. This leaves me with an ordered pair of (0,-1).....thus, the value of b is -1.