Imagine two wolves, a sister and her full-sibling brother, are working together to raise the sister's litter of 10 pups, fathered by an unrelated male. the brother could strike out on his own, in which case he would father 7 pups. however, if he leaves, only 5 pups of his sister's brood will survive. given that hamilton's rule says a behavior is favored if rb - c > 0, what should the brother do to maximize his fitness?