Step-by-step explanation:

While subtracting , the sign of each term of second expression changes & remove the parentheses.
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Combine like terms. Like terms are those which have the same base. Only coefficients of like terms can be added or subtracted.
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In standard from , the expression should be written in such a way that the power of variables goes from highest to lowest.

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Answer:
4^2
Step-by-step explanation:
The interior angle measures are 900 degrees
131+122+125+148+107+126 = 759
900-759 =141
X = 141
The answer would be a repeating decimal
Answer:
x = -8
Step-by-step explanation:
16+6-6x-4=-7x+3+7
Combine like terms
18 -6x = -7x+10
Add 7x to each side
18-6x+7x = -7x+7x+10
18+x = 10
Subtract 18 from each side
18+x-18 = 10-18
x = -8