Question

in our model rent is equel , q=(Wu-Wa)-2tr this simply comes from rent q such that net income anywhere in the city can only be as much as net income elsewhere in the countryside: Wu-2tr-q=Wa. (if this were not ture ,then there would either be immigration or outmigration.) now let the urban boundray r^ denote the inhabited location that is most distant from the CBD: compute r^?