Errors !

The equation is actually y=2x+9. You can figure this out simply by plugging in a (x,y) represented in the table and it would not work. The slope is not 10 because the y's go up by 10 and the x's go up by 5. Thinking of rise over run, 10/5 is reduced to 2.

The student did not plug the coordinate into the second equation. When you plug it into the second it does not work so it is not a solution.

The problem in this is that the first graph's line is suppose to be dotted. The second graph is suppose to be shaded above.

The slope line on number 20 should be dotted and on number 21 should be shaded below.