Answer: For the first scale, u would put a cube and 8 spheres. For the second, u would put the total which is 12 so 12 spheres.
Explanation:
The trash collected by all the three teams is shown by the 8 spheres and a box on one side of the scale. Since the weight was 12 pounds, it can be shown as 12 spheres on the other side of the scale
Im pretty sure this is right, Enjoy!