Which of the lines graphed in the diagram represents the equation 6x + 4y = 8

In order to easily discern which graph is a proper representation of 6x + 4y = 8, you first need to convert the equation to y = mx+ b, also known as slope-intercept form. Here's how you can do this:
6x + 4y = 8
4y = -6x + 8
y = -1.5x + 2
The +2 tells you that your line will intercept the vertical y-axis at (0, 2). This narrows it down to graphs a and d. Then, because you have a NEGATIVE number in front of your x (it's -1.5), you can tell that your graph will be going down as it moves from left to right. This leaves you with graph d as your answer!