21=a-(-7)

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Solution for 21=a-(-7) equation:


Simplifying
21 = a + -1(-7)

Multiply -1 * -7
21 = a + 7

Reorder the terms:
21 = 7 + a

Solving
21 = 7 + a

Solving for variable 'a'.

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

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

Combine like terms: a + -1a = 0
21 + -1a = 7 + 0
21 + -1a = 7

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

Combine like terms: 21 + -21 = 0
0 + -1a = 7 + -21
-1a = 7 + -21

Combine like terms: 7 + -21 = -14
-1a = -14

Divide each side by '-1'.
a = 14

Simplifying
a = 14

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