You have to look for -3 on the x axis, and then proceed vertically (in this case upwards) until you meet the graph.
We land about 1/2 square above the 12 mark on the y axis. Since one square is 1/2 unit, a half square would be 1/4 unit.
So, we can estimate [tex]f(-3)\approx 12.25[/tex]
