Select all the expressions that equal 6^-10

Can someone me and do the problem plz so i can understand it more better

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

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.