Given sets A and B, what is equal to (A B)'?

If there are 12 moths and some have 31 days and others have 30 days how many have 28 days?

Acourgette seed and a pumpkin seed is planted p(courgette seed germinates) 4/5 and p(pumpkin seed germinates) = 1/6 what is the probability that both seds germinate

Aprojectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. after how many seconds does the projectile take to reach its maximum height?