What number should be added to 77 to make the sum 0?
 77 –77 0 –76

Answer: -77

Step-by-step explanation:

Let the unknown number be x.

We have been asked to find the unknown x.

It is given that when the unknown x is added to 77, the sum will be zero. Thus the mathematical representation will be:

[tex]77+x=0[/tex]

Taking the unknown to one side of the equation ad solving:

[tex]x=0-77[/tex]

[tex]x=-77[/tex]

Thus the required number is -77.