Joe can put up a swing set in 3 hours. andy can put up a swing set in 5 hours. how long would it take joe and andy to put a swing set up if they worked together?

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