Mrs.Kennedy can divide 315 by 10 and then when she gets her answer she can round up to get her answer.
So,
9*27 + 2*31 - 28 = n
We use PEMDAS.
Multiply from left to right.
243 + 2*31 - 28 = n
243 + 62 - 28 = n
Add or subtract from left to right.
305 - 28 = n
277 = n
<span>x + 3y = 9
-x + y = -1
X = 3
Y = 2
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