Checking equations

When checking the equation, all you have to do is take the answer you get after solving the equation and substitute the X with the answer you got and resolve the equation from the beginning.

example: -3x - 5 = -20 ~original equation
+5 +5
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-3x = -15
-- --
-3 -3
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1x = 5 Check~ -3(5) - 5 = -20
-15 - 5 = -20
-20 = -20