These are 2 very different equations, and should be graphed very differently.
A
For Part A, we must first put this in Slope Intercept Form (SIF), which is y=mx+b where "m" is the slope and "b" is the y-intercept. To do this, we should solve like a normal equation for y.
2x+3y=12
-2x -2x
3y=-2x+12
/3 /3
y=-2/3x+4
Now that we have the proper equation, it is simply to graph! We should simply make a point at (0, 4), and then go down 2, right 3 until you are satisfied with your line.
B
Part B is a simple x value, which means you will draw a vertical line through 7 on the x-axis.
Below I have attached a clearly labeled graph that shows you examples of these lines. The red markings indicate x=7. The yellow circle shows you the y-intercept in Part A, while the yellow dots show you the slope in Part A.