X - y = 11
2x + y = 19

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.

Cd is the perpendicular bisector of both xy and st, and cy=20. find xy.

Can someone show me step by step how to do this?