Question 487173
<pre>
-12 = 3 - 2k - 3k

Combine -2k - 3k as -5k

-12 = 3 - 5k

Add -3 to both sides of the equation:

-12 =  3 - 5k
 -3   -3
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-15 =     -5k

Divide both sides by -5

 {{{(-15)/(-5)}}} = {{{(-5k)/(-5)}}}

Simplify:

 3 = {{{(cross(-5)k)/(cross(-5))}}}

 3 = k

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Checking:

-12 = 3 - 2k - 3k
-12 = 3 - 2(3) - 3(3)
-12 = 3 - 6 - 9
-12 = -12

Edwin</pre>