A tree with a height of 12 yards casts a shadow that is 33 yards long at
a certain time of day. At the same time, another tree nearby casts a
shadow that is 20 yards long. How tall is the second tree?

it can be derived from proportions , let height of the second tree be x here 12/33 = x/20 so, x = 12*20/33 = 7.27 yards is the answer.................................