The correct option is
Consider 1721 and 1021, which are like fractions as they have the same denominator.
While subtracting like fractions, we subtract the numerators and keep the denominator as it is.
i.e., 1721−1021=17−1021=721, which is equivalent to 13.
Similarly, 1215−915=315=15 and
Now consider the addition of the like fractions1015 and 515. We add the numerators up and keep the denominator as it is. Thus, 1015+515=10+515=1515=1