let
x------> the length of a room
y-----> the width of a room
we know that
Area of a room=x*y
Area of a room=432 ft²
so
432=x*y-----> equation 1
x=3y-----> equation 2
substitute equation 2 in equation 1
432=[3y]*y----->432=3y²
y²=432/3
y²=144----------> y=√144-----------> y=12 ft
x=3y-----> x=3*12-----> x=36 ft
the answer is
the width of the room is 12 ft
