Slope: Take two points from the graph, and do y-y, over x-x.
for ex. (1,2) and (2,4) do 4-2 over 2-1. your slope is 2/1= 2
y-intercept: find the one point on the graph that is exactly on the y-axis.
for ex. (4,0)= your y-intercept is 4
It should be 110 degrees, hope this helps
a. The marginal densities

and

b. This can be obtained by integrating the joint density over [0.25, 1] x [0.5, 1]:

Just divide 221 by 85. The answer was 2.6, or 2 3/5
X=21.6 I think is the answer if I did my math wrong