8a-(a+7)=21

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Solution for 8a-(a+7)=21 equation:


Simplifying
8a + -1(a + 7) = 21

Reorder the terms:
8a + -1(7 + a) = 21
8a + (7 * -1 + a * -1) = 21
8a + (-7 + -1a) = 21

Reorder the terms:
-7 + 8a + -1a = 21

Combine like terms: 8a + -1a = 7a
-7 + 7a = 21

Solving
-7 + 7a = 21

Solving for variable 'a'.

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

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

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

Combine like terms: 21 + 7 = 28
7a = 28

Divide each side by '7'.
a = 4

Simplifying
a = 4

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