7/12-(-3/4)+(-1/8)=Evalute the expression.  Do we have to find a common denominator for all three variables before we solve.

Expert Answers
Matthew Fonda eNotes educator| Certified Educator

To add or subtract fractions, finding a common denominator is generally the easiest method.

With this problem, we first notice that we are subtracting a negative number, and adding a negative number, so we can rewrite this as adding and subtracting.

`7/12 + 3/4 - 1/8 = ?`

We will then rewrite the terms using the common denominator 24:

`14/24 + 18/24 - 3/24 = ?`

At this point we can now simply add:

`14/24 + 18/24 - 3/34 = 29/24`

We notice that we cannot simplify any further, so we can report our answer as `29/24` , or equivalently as the mixed fraction `1 5/24`