Answer: 0
Step-by-step explanation: To subtract like fractions such as 6/7 - 6/7, we simply subtract the numerators and keep the original denominator.
So in this problem, we subtract 6 - 6 to get 0 and we keep the denominator of 7 which gives us 0/7.
When we have 0 in the numerator of a fraction, it simplifies to just 0.
This means that 6/7 - 6/7 = 0.