Complex sentence: The city requires new large housing developments in the DTES to set aside 20% of their units for social housing, some of which is rented at welfare rates, and some rents at rates up to hundreds of dollars a month more.
Split into simpler sentences: The city requires new large housing developments in the DTES to set aside 20% of their units for social housing. There is no requirement for how many social housing units must be rented at welfare rates; some units rent at rates up to hundreds of dollars a month more.