What do i do to answer this question

Need on this geometry question. explain how you did it.

Twenty points. 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

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30