my answer i got was -24/7 cant find the right answer !
It looks like your answer is upside-down.
7/8/(-3) is the same thing as 7/8 ÷ -3/1.
Now we have two fractions. To divide two fractions you flip the second one over so you change -3/1 into -1/3 and multiply.
7/8 x -1/3 = -7/24