Thank you for the opportunity to help you with your question!
9 - x = 23 + x
Put like terms together. Take 9 to the right side of the equal sign and the x on the right side to the left side of the equal sign. when numbers cross the equal sign, they change the mathematical sign before them. therefore:
-x - x = 23 - 9
-2x = 12
diving both side by (-2) gives
x = 12/-2
Hence x = -6
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