Use the substitution method to solve the system. {m+n=5m−n=3 what is the solution?

i found two solutions,   n = 2 • ± √3 = ± 3.4641

step-by-step explanation:

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

b. b < 1 might be the correct answer