Make r the subject of the formula: v=πr²h

This is called a literal equation, or an equation with multiple variables. You solve it the same as you solve any other equation, but the variables stay there the whole time.

If they want "r" to be the subject, then they want you to solve for r. This means that you need to get the variable r by itself on one side of the equation, but still have the equation be equivalent to it original form.

     I'm going to show you, in steps, how to solve this problem:

V=πr²h

Divide both sides by "π²h"
V/π²h=(πr²h)/π²h

V/(π²h)=r

Your answer is r=V/π²h

He needs 1 hour 40 minutes more to get the amount of sleep he likes or 1 2/3 hours

Step-by-step explanation:

Justin likes to get 7 hours of sleep.

He woke up after sleeping for 5 1/3 hour = 5 hours 20 mins

Number of more hours needed to get the amount of sleep he likes= 7 hours - 5 1/3 hours.

1 hour = 60 minutes

1/3 hours = 60/3 = 20 minutes

Hours         Minutes

7                     00       when we borrow 1 hour we borrow 60 minutes

5                    20

1                   40

He needs 1 hour 40 minutes more to get the amount of sleep he likes

or 1 2/3 hours