You might want to simplify the equation first. Basically, we'll use y = ax+b instead.

Should have been like this then you are able to graph.
To graph, you need to find the x-intercept and y-intercept.
(1) Find x-intercept, substitute y = 0

Thus, the graph has a x-intercept at (3,0). For those who are wondering where does the fractional 2 go, just multiply the whole equation by 2 to get rid of the fraction.
(2) Find y-intercept, substitute x = 0

Also 21/2 = 10.5, Thus the graph passes y-axis at (0, 10.5)
Now plot the graph, make a line from x-intercept and y-intercept and you should get like this (Picture below.)