Answer:
6 : 23
Step-by-step explanation:

Answer:
The error with mark’s work is that a negative times a negative will give a positive. So -3 times -5 is +15 not -15. Then 15 times -2 will get you -30.
Answer:
24
Step-by-step explanation:
Remember that straight lines are 180°. For #1 angle 1 would be 40°, since 140°+40°=180°
No they are not because it can be simplified