The unit digit of a two digits are reversed the new number is 18 more than the original number

it will cost dollar $540

the living room is 3 which means if we divide 325/3 then we get $108

therefore if 1part of the living room cost $108 and 3 costed $325

then total 5part of the room will cost 5*108 which gives $540

you need to rotate this triangle about the origin 270 degrees clockwise to create the full square.