Question

Twelve ounces of Brand X costs $1.14. Sixteen ounces of Brand Y costs $1.28. Brand X costs how much more per ounce than Brand Y.

Answer 1

"Per" means "divided by", so "cost per ounce" means "cost"/"ounces".

The difference in cost per ounce is
.. (1.14/12) -(1.28/16) = .095 -.08 = 0.015

Brand X costs 1.5¢ more per ounce than Brand Y.