We are give that the two triangles are proportional, this means that: BC/EF = CA/FD
We are also given that: BC = 9 units EF = 90 units CA = b (The value we want to calculate) FD = 360 units
Substitute with the givens in the proportionality relation mentioned above to get the value of b as follows: BC/EF = CA/FD 9/90 = b/360 b = (9/90) * 360 b = 36 units
