bài 2:
a: 3x+12=27
=>3x=27-12=15
=>x=15/3=5
b: (115+x)-54=46
=>x+115=54+46=100
=>x=100-115=-15
c: \(x⋮5\)
=>\(x\in B\left(5\right)\)
=>\(x\in\left\{0;5;10;15;20;...\right\}\)
mà 10<x<20
nên x=15
Bài 1:
a: 325+172+75
=(325+75)+172
=400+172
=572
b: \(53\cdot12+53\cdot172-53\cdot84\)
\(=53\left(12+172-84\right)\)
\(=53\cdot100=5300\)
c: \(\left(-25\right)\cdot7\cdot\left(-4\right)\cdot3\)
\(=25\cdot4\cdot7\cdot3\)
\(=21\cdot100=2100\)
d: \(1152-\left(-374+1152\right)\)
\(=1152+374-1152\)
=374
Đúng 2
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