21 3 (x 7) = x + 20 21 3x + 21 = x + 20 ⇒ 3x + 42 = x + 20 ⇒ 3x x = 20 42 ⇒ 4x = 22 ⇒ x = 224 = 112 ...

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Solving Equations with Variables on Both Sides

Solve: 21-3...

Question

Solve: $21 - 3 (x - 7) = x + 20$

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Solution

$21 - 3 (x - 7) = x + 20$
$21 - 3 x + 21 = x + 20$
$\Rightarrow - 3 x + 42 = x + 20$
$\Rightarrow - 3 x - x = 20 - 42$
$\Rightarrow - 4 x = - 22$
$\Rightarrow x = \frac{22}{4} = \frac{11}{2}$

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