This graph is composed of four straight line segments. You'll need to determine the slope, y-intercept and domain for each of them. Look at the first segment, the one on the extreme left. Verify yourself that the slope of this line segment is 1 and that the y-intercept would be 0 if you were to extend this segment all the way to the y-axis. Thus, the rule (formula, equation) for this line segment would be f(x)=1x+0, or just f(x)=x, for (-3,-1). Use a similar approach to write rules for the remaining three line segments.
Present your answer like this:
x, (-3,-1)
f(x) = -1, (-1,0)
one more here
one more here