Assuming a year has $360$ days and $12$ months of $30$ days each.
I can say that adding $5$ days $2$ months and $15$ years to $17/10/2014 (dd/mm/yyyy)$, is $22$ days $12$ months and $2029$ years
Now since $$(2014*360days)+(10*30days)+17days=725357\text{ days}$$ and $$(15*360days)+(2*30days)+5days=5465\text{ days}$$
Then diving the number of days by $360$ to get the years why doesn't $$(725357+5465)/360 =2029.ssss \text{ where s is some decimal value}$$
And instead it equals to $$(725357+5465)/360 =2030.ssss \text{ where s is some decimal value}$$
Because $12$ months is a year, so $22$ days $12$ months $2029$ years is $22$ days $2030$ years.