You would put a straight line going horizontally through 5. Like this picture shows. If it were x = 5, for example, then it would go up and down through 5.
To graph the equation y = 5, we must know what horizontal lines are. Horizontal lines are lines that are written in the form y = c, with y being the variable y and c being a constant. The c represents at which y value the horizontal line will form. That means that in this case, the horizontal line will be at the 5 value of y. Now we have to graph a horizontal line at 5. Doing this gives us:
