Step-by-step explanation: To shift the graphs up and down on the coordinate system, you need to manipulate or change the y-intercepts.
The y-intercept is just the constant term in the equation.
As long as the slopes remain the same, the graphs can be
translated up or down by changing the constant value.
Take a look at these lines graphed below.
Notice that y = x + 11 is the same as y = x + 4 but
y = x + 11 is translated 7 units down to get y = x + 4.