The total amount of money from washing cars is 3 * $10 = $<<3*10=30>>30
The total amount of money from mowing lawns 2 * $13 = $<<2*13=26>>26
The total amount of money Stormi makes is $30 + $26 = $<<30+26=56>>56
Stormi still needs to make $80 - $56 = $<<80-56=24>>24
#### 24