Because 10/2 = 5, at Sam's club you get twice the beans. Thus, simply multiply 2.8*2 = 5.60. Because $5.60>$4.90, the village market is the worse place to buy.
The unit price at the village market is 2.80 / 5 = 0.56 and the unit price at Sam's Club is 4.90 / 10 = 0.49. Since 0.49 < 0.56, the answer is Sam's Club.
