We know that
• Henry started with 3 packages of pencils.
,
• He used 4 pencils each week.
,
• The school year is 36 weeks.
Assuming that each package of pencils has 8, he would have

Henry has 24 pencils in total. But he uses 4 pencils each week, so let's divide

Therefore, Henry will run out of pencils in week 6.