CPM Homework Help : CALC Problem 7-21

Patrick, who is $6$ feet tall, is walking way from a $10$ -foot tall lamppost. If he casts a shadow that is $12.5$ ft long, how far from the lamppost is he?

Hint:

Do you see two similar overlapping triangles? Recall that similar triangles have proportional sides. Set up a proportion and solve for $x$ .