Question

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Answer 1

a - (a-b) = a - a + b = b
x+(x-y)+(-x+y) = x+x-y-x+y = x
bc - (bc-bc) = bc - bc + bc = bc
3a - (-4a+5b) = 3a + 4a - 5b = 7a - 5b
(-4m+7n)+(-3m+2n)-m = -4m+7n-3m+2n-m = - 8m + 9n