Lisa and Peter are selling chocolate bars door to door. Lisa sold three and a half boxes of chocolate bars, and Peter sold four and a half boxes. They sold 64 chocolate bars together. How many chocolate bars are in a box?
Let B stand for the number of chocolate bars in a box.
Lisa sold 3 1/2 * B bars.
Peter sold 4 1/2 * B bars.
Together, they sold 3 1/2 * B + 4 1/2 * B = 8B = 64 bars.
Therefore, there are B = 64 / 8 = <<64/8=8>>8 chocolate bars in a box.
#### 8