Answer: He should pack 9 elf bread for a 12 day trip.
Explanation:
Since, The number of loaves of el bread he used to pack for 8 days trip = 6 
⇒ The number of loaves of el bread he used to pack for 1 days trip = 

⇒ The number of loaves of el bread he used to pack for 12 days trip 


Hence, he should pack 9 elf bread for a 12 day trip.