Answer:
In order to find the total inches Jasper grew during the two years, we have to add up the total inches he grew when he was 15 and the total inches he grew when he was 16. Therefore, we have to add 1/10 and 3/10 together.
1/10 + 3/10 = 4/10, or 2/5.
Therefore, Jasper grew a total of 2/5 inches in those two years.