Answer:
1 pint (or 16 oz)
Step-by-step explanation:
1. convert the amout of pints into ounces (multiply 18 (pints) times 16 oz in a pint) 18 * 16 = 288 total ounces
2. determin how many ounces are used by students (multiply 68 (students) by 4 oz) 68 * 4 = 272 ounces uses
3. find the difference (subtract 288-272 = 16 oz left over)
16 oz = 1 pint