Tìm x
a) 12 : x = 3 b) 21 : x = 7 c) 30 : x = 3
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d) X : 7 = 4 e) 20 : x = 5 f) X x 6 = 42
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a) 12 : x = 3
X = 12 : 3
X = 4
b) 21 : x = 7
X = 21 : 7
X = 3
c) 30 : x = 3
X = 30 : 3
X = 10
d) X : 7 = 4
X = 4 x 7
X = 28
e) 20 : x = 5
X = 20 : 5
X = 4
f) X x 6 = 42
X = 42 : 6
X = 7