Question 95080
A variable is an unknown number that will change or variable depending on the equation or math problem.  Usually a variable is represented by x, y or z.
When the correct number for the variable or variables are plugged into the problem, it will make the problem (or equation) a true statement.

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Difference means to subtract two numbers:
8-x
"x" can vary or change.  Since this is not an equation, "x" can equal any number.
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But if 8-x=2
Than "x" can only equal 6
8-6=2 becasue no other number will make this a true statement.

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I hope this helps!