Answer:
4 cases
Explanation:
Find out how many pencils per case:
1 case = 24 boxes
1 box = 12 pencils
1 case = 24•12 = 288 pencils
Divide the amount of needed pencils (900) by how many per case there are (288) to find how many cases you need:
900÷288=3.125 (or 3 1/8)
Since you can't get a part of a case (for the 1/8 of a case you need), you will need to round up to 4 cases.