Which fraction is represented by point A on the number line? 0
А
-0 -1
о
IT
os
O 1

The answer is the third choice: -1/4.
Here’s why: if you count from 0 to 1 or -1, it’s 4 steps. That means the fraction would have a denominator of 4, if there were 5 parts, then the denominator would be 5...and so on. The numerator is 1 because 0 to the point is 1 step. But now why negative? Because everything to the left of 0 on the number line will be negative, everything right of 0 on the number line will be positive.
Hope this also helped you to understand for future problems like this.

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction