Answer:
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Step-by-step explanation:

Combine all like terms.

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Multiply both sides by -1.
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Answer:
-165
Step-by-step explanation:
Answer:
B a = 180 -77-60
Step-by-step explanation:
The angles add to 180 degrees since they form a straight line
77+ 60+a = 180
a = 180 -77-60
Mentally
As they are numbers which you can do mental math with since they are whole numbers.
Answer:
5
Step-by-step explanation:
Because if you divide them all you see that in 5 you don't get a whole number