21=x+2x

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Solution for 21=x+2x equation:


Simplifying
21 = x + 2x

Combine like terms: x + 2x = 3x
21 = 3x

Solving
21 = 3x

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-3x' to each side of the equation.
21 + -3x = 3x + -3x

Combine like terms: 3x + -3x = 0
21 + -3x = 0

Add '-21' to each side of the equation.
21 + -21 + -3x = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -3x = 0 + -21
-3x = 0 + -21

Combine like terms: 0 + -21 = -21
-3x = -21

Divide each side by '-3'.
x = 7

Simplifying
x = 7

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