How do you solve $21- ( x + 9) = 8x - 6?$

Question

802 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-12-15T16:05:38

$x = 2$

First, expand the term in parenthesis and then group and combine like terms on the left side of the equation:

$21 - x - 9 = 8x - 6$

$21 - 9 - x = 8x - 6$

$12 - x = 8x - 6$

Now, isolate the $x$ terms on one side of the equation and the constants on the other side of the equation while keeping the equation balanced:

$12 - x + x + 6 = 8x + x - 6 + 6$

$12 - 0 + 6 = (8 + 1)x - 0$

$12 + 6 = 9x$

$18 = 9x$

Now solve for $x$ while keeping the equation balanced:

$18/9 = (9x)/9$

$2 = (cancel(9)x)/cancel(9)$

$2 = x$

How do you solve 21- ( x + 9) = 8x - 6?21- ( x + 9) = 8x - 6?