Using the slot method and multiple cases... If I roll 4 dice, what is the probability of rolling 3 sixes?

Ineed to know the answer right now! !

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

The areas of two similar triangles are 72dm2 and 50dm2. the sum of their perimeters is 226dm. what is the perimeter of each of these triangles?