NSS.....the first two contraints, x ≥ 0 and y ≥ 0, just tell us that the portion of the graph that we are interested in lies in the frist quadrant........so.....I won't graph those
See the others, here : https://www.desmos.com/calculator/dr3w5xlcw1
Any maximum - or minimum - occurs at a "corner point" ......there is only one corner point on this graph at (2.5, 2.5).....and this is the point that maximizes 7x - 3y