PLEASE I NEED HELP I AM STUCK PLEASE

We're adding n and m onto k to get P. Undo these operations to isolate k. So we subtract m from both sides

P = k+n+m

P-m = k+n+m-m

P-m = k+n

and we subtract n from both sides

P-m = k+n

P-m-n = k+n-n

P-m-n = k

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