What is 100% of the mass ?
It would last 13.5 weeks because you would make a proportion:
12/16 = x/18 and then cross multiply. You would get 216=16x, then you have to divide both sides by 16 to get x = 13.5
It is just asking you to reorder the number so that the smallest number is first and the largest number is last.
The answer is: 8, 8.261, 8.4, 8.634