Answer: 33.5 millimeter balls in each
Step-by-step explanation: 1. 27 millimeter balls
2. 40 millimeter balls
3. Add 40 + 27 = 67 millimeter balls
4. To put it in equally you would have to divide 67 by 2
5. 67/2 = 33.5, since 33 + 33 = 66 and 0.5 + 0.5 = 1, (the 0.5 comes from the 33.5).
Note: Multiplication is the reversed order of division and for example A+A, it is the same as A x 2. The reversed order of 67/2 is 33.5 x 2.
7. Answer = 33.5