I have 2 tree's the young tree is 5 meter's high and has a shadow of 2.0 meter's. the older tree has a shadow of 3.5 meter's How tall is the older tree.

Answer 1

Tree1/shadow1=tree2/shadow2
so by proportion:
tree2=(tree1/shadow1)*shadow2
=(5/2)*3.5
Can you take it from here?

Answer 2

Alice is 1.5m tall. She is standing 3m from the foot of a lamppost. The lamp is 4.5m from the ground. How long will Alice's shadow be?