Answer:
- as written, -4/15
- with parentheses, 4
Explanation:
As the problem is written, you have ...

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If you add parentheses to include x in the numerator, then you have ...
x/4 = (x +1)/5

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Additional comment
We include the second working because it is a fairly common mistake to neglect to put parentheses around a numerator or denominator. The solutions to such problems are not often fractions, so we suspect you intend the latter form.