Which is not equivalent to A x + B y = C ? y = C B − A B x y = C B − A B x y = C − A x B y = C − A ⁢ x B y = C B − A x B y = C B − A ⁢ x B y = C − A B x

Mr. roseanne will buy 12 1/2 pounds beef for for a cookout. the price for the first 3 pounds of beef is $4.99 per pound. after that, the price is $4.49 per pound. how much will mr.roshan pay for the beef