A tree casts a shadow x = 100 ft long when a vertical rod 6.0 ft high casts a shadow 4.0 ft long. How tall is the tree? (Round your answer using the rules for working with measurements.)

You need to set up a proportion first, so x/100=6/4 solve for the proportion 100 times 6 equals 600, then 4 times x equals 4x. Divided by 600 by 4 which is 150. So your answer is going to be that the tree is 150 feet tall : D.