Question: John raises butterflies.  He has 4 jars of 10 caterpillars each.  40% of them fail to become butterflies, but the rest become caterpillars.    He sells the butterflies for $3 each.  How much money does he make? Is final answer 72?
Answer: He has 4*10=<<4*10=40>>40 caterpillars.
40*.4=<<40*.4=16>>16 fail to form.
That means he has 40-16=<<40-16=24>>24 butterflies.
So he makes 24*3=$<<24*3=72>>72.
#### 72