A wire of length $340$ mm is to be cut into two parts. One of the parts is to be made into a square and the other into a rectangle where sides are in the ratio of $1:2$. What is the length of the square (in mm) such that the combined area of the square and the rectagle is a $\textbf{MINIMUM?}$
- $30$
- $40$
- $120$
- $180$