in order to calculate this, we need to make the fractions have a common denominator. to do that, we find the smallest multiple that both 8 and 4 share. luckily 4 is a factor of 8, so we only need to change the one fraction.
to change 3/4 to have a denominator of 8, we will multiply the fraction by 2/2 since whatever you do to the bottom you must also do to the top.
3/4 * 2/2 = 6/8
now we can add the fractions to see how many miles were walked.
6/8 + 3/8 = 9/8, which can be simplified to 1 1/8 miles.
hope this helps!