Hello from MrBillDoesMath!
Answer: x = 1
Discussion :
Per the author, the equation to solve is 12 = 5x + 7
Isolate the "x" variable by subtracting 7 from both sides of the equation:
12 = 5x + 7
-7 = -7
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12-7 = 5x + 0
or
5 = 5x
Dividing both sides by 5 gives x - 1
Regards, MrB