James makes potatoes for a group.  Each person eats 1.5 pounds of potatoes.  He makes potatoes for 40 people.  A 20-pound bag of potatoes costs $5.  How much does it cost?
He needs 1.5*40=<<1.5*40=60>>60 pounds of potatoes
So he needs to buy 60/20=<<60/20=3>>3 bags of potatoes
So it cost 3*5=$<<3*5=15>>15
#### 15