Carl buys index cards for his class.  He gives each student 10 index cards.  He teaches 6 periods a day and each class has 30 students.  If a 50 pack of index cards cost $3 how much did he spend on them all?
He has 30*6=<T>multiply(30, 6)=180 students
So he needs to buy 180*10=<T>multiply(180, 10)=1800 index cards
That means he needs to buy 1800/50=<T>divide(1800, 50)=36.0 packs of index cards
So he spends 36*3=$<T>multiply(36, 3)=108
