Question: 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? Think carefully first, then make a decision:
He bought 12 - 3 - 2 = 7 blue notebooks. He paid 3 * $4 = $12 for red notebooks. He paid 2 * $2 = $4 for green notebooks. He spent $37 - $12 - $4 = $21 on blue notebooks. Each blue notebook costs $21 / 7 = $3. So the answer is 3.