Cách làm cho bạn:
a) 219 – 7.(x + 1) = 100
$\Rightarrow$ 7.(x + 1) = 219 – 100
$\Rightarrow$ 7.(x + 1) = 119
$\Rightarrow$ x + 1 = 119 : 7
$\Rightarrow$ x + 1 = 17
$\Rightarrow$ x = 16.
b) (3x – 6). 3 = 34
$\Rightarrow$ 3x – 6 = 34: 3
$\Rightarrow$ 3x – 6 = 34-1
$\Rightarrow$ 3x – 6 = 33
$\Rightarrow$ 3x – 6 = 27
$\Rightarrow$ 3x = 33
$\Rightarrow$ x = 11.
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