Many years ago, a cruise liner sank in the middle of the Pacific Ocean.
The survivors luckily landed on a remote desert island.
There was enough food for the 220 people to last three weeks.
Six days later a rescue ship appeared, unluckily this ship also sank, leaving an additional 55 people stranded on the island to now share the original rationed food.
The food obviously had to be re-rationed, but everyone was now on one-half of the original ration, so how many days in total would the food last for, from the day of the original sinking?