I'm not following. What's the question?
When rounding the 4 you look to the right of the number, which is the 4, and if the number is higher than 5 you would change the 4 to 5.
Therefore: 71.5
Answer:
if they are both equeal
Step-by-step explanation:

Actually Welcome to the concept of Radioactive decay.
So the left would be 30 grams.