Michael is calculating the sum of some positive and some negative numbers. Michael used a number line to model
the sum.
-60-50-40-30-20-10 0 10 20 30 40 50 60
The model did not help Michael determine the sum.
How could Michael improve his model to allow him to determine the sum?
Answers:
If he made all the arrows point to the left, the last arrow's tip would be at the sum.

If he made all the arrows point to the right, the last arrow's tip would be at the sum.

If he put the starting point of each arrow at the tip of the previous arrow, the last arrow's tip would be at
sum.