I have taken out a residential lease with one housemate. Our relations have deteriorated, and I would like to break the lease without financial penalty. In preparing the lease, the landlady failed to edit a previous version and listed two different rents ($1250 and 1400). Is the lease invalid, thus defaulting us to month-to-month status? Does the fact that we have paid the higher rent for the last six months have any bearing on this question?