Division is a "stronger" operation than addition, so we perform the operation 5 ÷ 70 first, getting 5/70 = 1/14 as a result.
We could either write 1/14 + 15 as the mixed number 15 1/14, or we could convert it to a mixed number to an improper fraction. Since there are 14/14 in one whole, 15 wholes is the same as (15 x 14)/14 = 210/14. Adding in the 1/14, we find that