Hi Julio.
This is a question involving subtraction of fractions and common denominators.
Julio runs 2.5 miles everyday.
We can express this as a mixed number 2 1/2, or as an improper fraction 5/2
He's already run 7/8 mile.
5/2 - 7/8 = how much further he has to run.
But one denominator is 2 and the other is 8 so we can't subtract yet. We need to restate on or both fractions so that they have the same denominator.
Notice that 2x4=8 so we multiply the first fraction by 4/4 so that the the denominator is 8. Notice 4/4=1 so we are not changing the value.
(5/2)(4/4) - 7/8
20/8 - 7/8 = 13/8 = 1 5/8 miles
