SOLUTION: A tree casts a shadow that is 15 feet long. At the same time, a building casts a shadow that is 21 feet long. If the building is 16 feet taller than the tree, how tall is the build

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: A tree casts a shadow that is 15 feet long. At the same time, a building casts a shadow that is 21 feet long. If the building is 16 feet taller than the tree, how tall is the build      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1012292: A tree casts a shadow that is 15 feet long. At the same time, a building casts a shadow that is 21 feet long. If the building is 16 feet taller than the tree, how tall is the building?
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Let us call the height of the tree, x.
Then we can write the proportion
15%2Fx+=+21%2F%28x%2B16%29
Now cross multiply and get
21x = 15(x+16)
21x = 15x + 240
6x = 240
x = 40 feet
The building is x + 16, or 56 feet tall.