57 degrees because 180-123= 57 degrees
Answer:

Step-by-step explanation:
- Simplify




- Find the additive inverse of
by using its property - <em>"Sum of a number & its additive inverse is always zero". </em>Assume that 'x' is an additive inverse of
.


- Simplify




- Now, find the product of
& 


Answer:
-7
Step-by-step explanation:
-10 - -3
- 10 + 3
-7
(a double negative becomes a positive)