Answer: -7/8
Explanation:
you need to find a common denominator for all of them
in this case it would be 24
2 18/24 -(- 1 12/24) + (-20/24) -(-9/24) - (+ 4 16/24)
2 18/24 + 1 12/24 - 20/24 + 9/24 - 4 16/24
4 6/24 - 20/24 + 9/24 - 4 16/24
3 10/24 + 9/24 - 4 16/24
3 19/24 - 4 16/24
- 21/24
-7/8