### Instruction: Mike spent 37 dollars on notebooks.  He bought a total of 12 notebooks.  He bought 3 red notebooks at 4 dollars each, 2 green notebooks at 2 dollars each, and the rest were blue notebooks.  How much does each blue notebook cost?### Response: He bought 12-3-2=7 blue notebooks.
He spent 3*$4=$12 on red notebooks.
He spent 2*$2=$4 on green notebooks.
He spent $37-$12-$4=$21 on blue notebooks.
Each blue notebook costs $21/7=$3.
The answer is 3