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a,5.7.77-7.60+7.7.25-15.6.7
=7.385-7.60+175.7-90.7
=7.(385-60+175-90)
=7.410
=2870
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a ) 2.12.53 + 6.87.4 - 120.8
= 24.53 + 24.87 - 24.5.8
= 24.53 + 24.87 - 24.40
= 24.(53 + 87 - 40)
= 24.100
=2400.
b ) 5.7.77 - 7.60 + 49.25 - 15.42
=7.385 - 7.60 + 7.7.25 - 15.6.7
=7.385 - 7.60 + 7.175 - 90.7
=7.(385 - 60 + 175 - 90)
=7.410
=2870
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53 . 39 + 47 . 39 - 53 . 21 - 47 . 21
= 53 . (39-21) + 47 . (93-21)
=53 . 18 + 47 . 18
= (53 +47) . 18
= 100 .18
=1800
2 . 53 . 12 + 4 . 6 . 87 - 3 . 8 . 40
=24 . 53 + 24 . 87 - 24 . 40
=24 . (53+87-40)
= 24 . 100
= 2400
5 . 7 . 77 - 7 . 60 +49 . 25 -15 . 42.
= 5 . 7 . 77 - 7 . 5 . 12 + 49 . 5 . 5 - 5 . 3 . 42.
= 5 . 539 - 84 . 5 +245 . 5 -5 . 126
= 5 . (539 - 84 + 245 -126)
= 5 . 574
= 2870
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b: \(=66\cdot\left(25+75+34+66\right)=66\cdot200=13200\)
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5 . 7 . 77 - 7 . 60 + 49 . 25 - 15 . 42 = 2870
Tích ủng hộ mik thoát khỏi điểm âm nha
\(5.7.77-7.60+49.25-15.42\)
\(=5.7.77-7.5.12+49.5.5-5.3.42\)
\(=5.539-84.5+245.5-5.126\)
\(=5.\left(539-84+245-126\right)\)
\(=5.547\)
\(=2870\)
3140