What is: 1/1+a+b^-1 + 1/1+b+c^-1 + 1/1+c+a^-1 please write the steps and explain

The expression:

It is possible that there are values for a, b, and c, but are omitted. If this is not the case, then the expression can be rewritten in another form. These are about all that can be done.

The second case is more plausible, given there are no values given for a, b, and c.

The expression can be rewritten as:

When a number has an index of -1, it is the same as taking the reciprocal of the number.

That is;

Therefore, the whole expression gives:

Taking the common denominator in the first three expressions, we have

It is also possible to take the common denominator of the whole whole expression, this will however, make the expression look more tedious, rather than simple.