Let
be the amount of soda contained by Bottle A and
be the amount of soda contained by Bottle B. We can track the changes in amounts of soda in each bottle. First, Bottle A contains
ounces, and Bottle B contains
. At the next step, A is reduced by
ounces, and B gains
ounces, so A has
and B has
ounces. Then, A is increased by
ounces and
is reduced by the same, so A has
and B has
ounces. Finally, B is increased by
ounces and A is decreased by the same, so A has
ounces and B has
ounces. We are given that
, and we are looking for
. Adding
to
gives
. Adding
to
gives
, or
. So,
, or
. Thus,
ounces.