7r+21=r-9

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Solution for 7r+21=r-9 equation:


Simplifying
7r + 21 = r + -9

Reorder the terms:
21 + 7r = r + -9

Reorder the terms:
21 + 7r = -9 + r

Solving
21 + 7r = -9 + r

Solving for variable 'r'.

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

Add '-1r' to each side of the equation.
21 + 7r + -1r = -9 + r + -1r

Combine like terms: 7r + -1r = 6r
21 + 6r = -9 + r + -1r

Combine like terms: r + -1r = 0
21 + 6r = -9 + 0
21 + 6r = -9

Add '-21' to each side of the equation.
21 + -21 + 6r = -9 + -21

Combine like terms: 21 + -21 = 0
0 + 6r = -9 + -21
6r = -9 + -21

Combine like terms: -9 + -21 = -30
6r = -30

Divide each side by '6'.
r = -5

Simplifying
r = -5

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