What's the lowest common multiple of 8 and 4

Math each whole number with a rational, exponential expression

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?

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)