Hey how is everyone's morning going so far

How do you use the additive inverse to evaluate an expression that uses subtraction in a full sentence

The sum of two numbers is 86, and their difference is 20. find the two numbers

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