Your local grocery store is having a special on Vitamin Water. They are selling a 12-pack of 20 oz bottles for $11.50. The 32 oz bottles are also on sale for $1.45. Should you buy one 12-pack of 20 oz bottles or eight 32 oz bottles?
This one is a bit tricky because we can't compare the cost per bottle, since the bottles are different sizes. Instead, we need to compare the cost per total ounces.