I don't understand this is urgent, please help

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)

If 3 3/4 lb. of candy costs 20.25 how much would 1lb. of candy cost

Robert has 78 tomato lants and 56 cucumber plants .he wants to plant them in rows that only have one type of plant in each row with the same number of plants in each row. how many plants should he put in each row and how many rows of each type of plant will he need