Answer:
-23/56
Explanation:
-1/8-2/7
= -7+8×-2
----------------
8×7
=-7-16/56
=-23/56
BTW. . This method is called the butterfly method.. in which we must cross multiply the numerators and denominators.. and multiply the denominator together (if they are co-primes) to get the LCM in the denominator of the sum..