Hello!
Let's write this as a system of equations.
L=3w
wL=432
Let's plug in our value for L into the second equation, and solve for w.
w(3w)=432
3w²=432
w²=144
w=12
Now, let's plug our w value into the first equation.
L=3(12)
L=36
Therefore, the length is 36 and the width is 12.
I hope this helps!