What is the probability you roll at least three on a dice

Icould really use some with this question.

The architect's side view drawing of a saltbox-style house shows a post that supports the roof ridge. the support post is 8 ft tall. the distance from the front of the house to the support post is less than the distance from the post to the back of the house. how far from the front of the house is the support post positioned?

What is the measure of angle x? a.101 b.158 c.44 d.79