We calculate the dimensions of a room either on paper or in reality, based on the given scale (or scale ratio). The last problem has to do with changing the scale in a scale drawing. It asks for the dimensions if a rectangle that's drawn at scale 1:50 is now drawn at scale 1:80 instead.
How to calculate distances on the map or in reality using the map scale
Math Mammoth Grade 7 curriculum (pre-algebra)