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 $3 how much did he spend on them all?
He has 30*6=
<gadget id="calculator">30*6</gadget>
<output>180</output>
180 students.
So he needs to buy 180*10=
<gadget id="calculator">180*10</gadget>
<output>1_800</output>
1800 index cards.
That means he needs to buy 1800/50=
<gadget id="calculator">1800/50</gadget>
<output>36</output>
36 packs of index cards.
So he spends 36*3=$
<gadget id="calculator">36*3</gadget>
<output>108</output>
108.

<result>108</result>