Shadow:
10 feet long (tree) ... 4 feet long (Javier)
Real situation:
t feet high = ? (tree) ... 5 feet tall (Javier)
If you would like to know what is the estimated height of the tree, you can calculate this using the following steps:
10 5 = 4 t
50 = 4 * t /4
t = 50 / 4
t = 12.5 feet high
Result: The estimated height of the tree is 12.5 feet.