Lizzy: Peter bought 4 new notebooks for school. 2 of them are green, one is black and the other one is pink. The total cost was $45. If the black notebook cost $15, and the pink one cost $10, how much did the green notebooks cost each?.
Me: Hmmm, let me think. I think this is the detailed solution:
The black and pink notebook cost a total of $15 + $10 = $25. The green notebooks cost a total of $45 - $25 = $20. Each green notebook cost $20 / 2 = $10. Final answer: 10.