2/3 + 1/2 equals what and how to arrive at the answer

Factor this polynomial completely x^2-64

Mr. brettler is hanging up a 5-foot tall rectangular welcome sign in the gym. he has drawn a sketch on a coordinate grid. he has the lower vertices of the sign at (9, –3) and (–6, –3). where would the upper vertices be on the grid?

The volume of a cube-shaped shipping container is 13,824 cubic inches. find the edge length of the shipping container.