Hello,
A and C are functions.
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Answer:
B
Step-by-step explanation:
Since equalateral all angles are 60. 60 - 69 = -9.
Answer: 
Step-by-step explanation:

Answer:
3 hours.
If you need a detail explanation just ask.
Answer:
810 boys
Step-by-step explanation:
1800 students and 55% are girls.
100%-55%=45%
1800*0.45 = 810
1800*0.55 = 990
So there are 990 girls and 810 boys.
Hope this helps :)