A math question: the tarrytown riddle?

so this is a math question. between sing-sing and tarrytown i met my worthy friend, John Brown, and seven daughters , riding nags, and everyone had seven bags. In every bag there were thirty cats, and every cat had forty rats. besides a brood of fifty kittens, all but the nags ad bags wore mittens. mitten, kittens-cats, rats-bags, nags-Browns. How many were met between the towns?