So for the cranberry muffin, for every 12 (a dozen) it's $3 Banana nut muffin: for every 12, it's $4.32 take the $3 and divide it by 12 which is $0.25 for every cranberry muffin take $4.32 divide by 12 and you get $0.36 for every banana nut muffin so $0.25 + $0.36 = $0.61 Therefore the answer is B
For this case we have that by definition, the Greatest Common Factor or GFC of two or more numbers, is the largest number that divides them without leaving residue.
So, we have to:
We look for the factors of 18 and 36:
18: 1,2,3,6,9,18
36: 1, 2,3,4, 6,9,18 ...
It is observed that the GFC of both numbers is 18.