Why is 21/30 greater than 2/3

Find the area of the triangle shown 3 by 6

Suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet.

Which rule describes the composition of transformations that maps △abc to △a”b”c