Part A)
First, draw the graph of each of the given equations:
The graph of x+2y=4 is shown as a solid, orange line.
The graph of y=(-1/2)x+2 is shown as a dotted, blue line.
Notice that both graphs overlap.
A solution to the system of equations is a point shared by the graph of both lines. In this case, since both lines overlap, every point on the lines is a solution to the system of equations.
Therefore, the system has infinitely many solutions.
Part B)
The graph of 2x-y=1 is shown in green, and the graph of y=-3 is shown in purple:
As we can see, both lines intersect at (-1,-3).
Therefore, this system has one solution. The solution is (-1,-3).
