Jasmine, this is the solution:
Let x to represent the height of the rectangles, thus we have:
hA = 8 units
hB = 6 units
hC = 4 units
hD = 2 units
Now, we can estimate the ratios, as follows:
D:C = 2/4 = 1/2
D:B = 2/6 = 1/3
D:A = 2/8 = 1/4
C:B = 4/6 = 2/3
C:A = 4/8 = 1/2