In a big farm in Wisconsin, there are only hens and cows. When the owner counted the heads of the stock in the farm, the number summed up to $200$, while counting the number of legs, the number summed up to $540$. How many more hens were there in the farm ? Assume each cow had $4$ legs and each hen had $2$ legs.
- $70$
- $120$
- $60$
- $130$