Answer:
It would look like the picture I attached at the bottom.
Explanation:
We know that the slope is -3 and the y intercept is (0,4) (plugging in 0 for x will get you that point), and then you can just graph an equation like you normally would, using rise/run to go down 3 units for every one unit you go right, and plugging in easy x values to check your work.
It gets a little tricky because the question then adds the inequality, and we see that y is now less than or equal to the original equation.
Since it is less than, we can shade all the values below the graph.
(Also, you should probably note for future reference that if it was just less than, the shading would look the same while the graph itself would be dotted because the values on the line are nor included in the solution set).
Desmos is a great website to use if you're having trouble graphing in the future :)