Question

x+1 - x+2 = ?

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2x-8 12-3x

Answer 1

The problem as is is not without ambiguities.

You can clarify the question by typing the expression on a single line, remembering to enclose the numerator or denominator in parentheses, and not forgetting that multiplication and division have higher precedence over addition and subtraction.

For example:
(x+1)/(2x-8) - (x+2)/(12-3x)
would not be ambiguous.