3,100 mg is 3.1 grams as there a 1000 mg in a gram.
see attached picture for solutions:
Answer:

Step-by-step explanation:
We need to find ration numbers between -1 and 1.
Multiplying and dividing both -1 and 1 by 2.

and 
Now, the rational number between -2/2 and 2/2 is
.