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?
The black and pink notebook cost a total of $15 + $10 = $<<15+10=25>>25
The green notebooks cost a total of $45 - $25 = $<<45-25=20>>20
Each green notebook cost $20 / 2 = $<<20/2=10>>10
#### 10