Please help me answer this

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

Acompany produces packets of soap powder labeled “giant size 32 ounces.” the actual weight of soap powder in such a box has a normal distribution with a mean of 33 oz and a standard deviation of 0.7 oz. to avoid having dissatisfied customers, the company says a box of soap is considered underweight if it weighs less than 32 oz. to avoid losing money, it labels the top 5% (the heaviest 5%) overweight. how heavy does a box have to be for it to be labeled overweight?

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?