Is it permissible for an elderly woman to perform aqiqah for herself, and for how many people does a cow suffice in udhiyah, and how is it slaughtered?

It is permissible for an adult to perform an 'aqiqah for themselves if their father did not do so on their behalf. A cow is sufficient as an udhiyah (sacrificial animal) for seven people, and this is the view of most scholars. 'Umar and Malik, however, held the view that it is only sufficient for one person, unless the head of the household intends to include his family members in the reward. The Sunnah for cattle is that they are slaughtered in the same manner as sheep.