Question

a 24 foot tall tree cast a 30 foot long. a 4 foot tall child is standing nearby how long is the child's shadow

Answer 1

You put it in a ratio so it's 24/30 = x/4 so the answer is 3.2 feet

Answer 2

If a 24 foot tall tree cast a 30 foot long shadow, then the ratio of that is 4:5.
So, for the 4 foot tall child, multiply by 4/5 (0.8) and you get 3.2.