For low density sea otter populations in the North Pacific Ocean, the overall annual per capita birth rate (b) is about 0.7 and the death rate is about 0.5. Birth rate is not density-dependent but death rate is density-dependent, such that d’ = d+cN (where N = number of otters per km of coastline). If c = 0.0133, what is the carrying capacity density of sea otters in number of animals per km of coastline?