Sally plans to run 12 miles. She ran 5 1/8 miles and then stopped for a water break. How many miles does Sakky have left to run?

So,

We can just subtract the fractions without converting any denominators. To do that, we can split the subtraction problem up as follows:

12 - 5 - 1/8

7 - 1/8

6 7/8

Sally still has 6 7/8 or 6.875 miles to run.