(a) In order to determine how much juice can drink each student, calculate the quotient between the number of liter (3 liters) and the total number of student (10 students), as follow:
hence, each student can take 3/10 liters.
(b) The equation which describes the given situation is:
where you have added the amount of juice each student can take, and this sum must be equal to the total amount of juice, which is 3 liters