A fortnight is a unit of time equal to 14 days.
First calculate number of weeks, days, months and dog years:
1. number of weeks: 13·2=26
2. number of days: 26·7=182
3. number of months: 182÷30=6,07
4. number of dog years: 6,07÷12=0,505
First dog year is equivalent of 15 human years: 0,505·15 = 7,58.