65 : 6.99 or 120 : 12.99, you could just multiply the ratios and compare each price to the same amount of ounces. So, 65 x 120 or 120 x 65 = 7800. Just multiply the prices for each respectively as well, so 6.99 x 120 = 838.8 and 12.99 x 65 = 844.35. So it is 65 : 6.99 = 7800 : 838.8 and 120 : 12.99 = 7800 : 844.35
838.8 < 844.35 so 65 ounces for 6.99 is the better buy.
