Tìm x
a) X + 15 = 20 b) X – 18 = 16 c) 72 – x = 50
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d) X x 7 = 42 e) X : 7 = 5 f) 49 : x = 7
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a) X + 15 = 20
X = 20 – 15
X = 5
b) X – 18 = 16
X = 16 + 18
X = 34
c) 72 – x = 50
X = 72 -50
X =22
d) X x 7 = 42
X= 42 : 7
X = 6
e) X : 7 = 5
X = 5 x 7
X = 35
f) 49 : x = 7
X = 49: 7
X = 7
