Giải thích các bước giải:
a, A=727-(182+327)
A = 727-182-327
A = (727-327)-182
A = 400-182
A= 218
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b, B=(258-79)-(111-90)
B = 258-79-111+90
B = 258-(79+111-90)
B = 258-100
B = 158
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c, C= (871-28)+(229-72)
C = 871-28+229-72
C = (871+229)-(28+72)
C = 1100-100
C = 1000
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d, D=(689-31)-(269-11)
D = 689-31-269+11
D = (689+11)-(31+269)
D = 700-300
D = 400
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