Given:
b) First the two lines are graphed,

Now, yoshi wants to add one more equation,

The graph is represented as,
In the above graph the green line represents the y=2x+1 and it lies between the line y= 2x+3 and y= 2x-2.
c) The graph of the line y = -2x +1
It is observed that the green line y= -2x+1 intersects both the lines y= 2x+3 and y= 2x-2.