# Thread: Solving Multi-Step Equations: 21 = 6 - x - 4x

1. ## Solving Multi-Step Equations: 21 = 6 - x - 4x

I have a question, here is the problem 21=6-x-4x. And then I need to know how to check the answer. I would like you to reply as soon as possible please. I thank you for your help to. And when you reply could you tell me how long it regularly takes to reply.

2. Hello, math87690!

So many variable I can't tell you how long it take to reply.

You can check your answer by filling what you found $x$ to be and see if the equation is balanced (same number on both side of the equations).

So with that being said:

$\L \;21\,=\,6\,-x\,-4x$

Combine like terms: $\L \;21\,=\,6\,-5x$

Subtract 6: $\L \;15\,=\,-5x$

Divide by -5: $\L \;-3\,=\,x$

...........Transitive Property: $\L \;x\,=\,-3$

Now you fill $x$ back in our original equation ($21\,=\,6\,-x\,-4x$) and see if it is balanced.

3. ## Re: Solving Multi-Step Equations: 21 = 6 - x - 4x

Originally Posted by math87690
I have a question, here is the problem 21=6-x-4x.
Keep it simple
5x + 21 = 6
Subtract 21 from each sides:
5x = -15
Divide each side by 5:
x = -3

4. ## here's the proof it worked

here's the proof it worked: I assigned -3 for x then plugged in the right hand side of the equation which, with x equivalent to -3, should equal 21 (the left side of the equation)

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