Even though Rao's allowance increased by the same dollar amount each time, it did not increase by the same percentage rate. His first increase represented a $75$ percent rate of change. His second increase represented a $43$ percent rate of change. How could Rao use this information to ask his parents for an additional increase in his allowance?

Because the dollar amounts are the same, Rao has no case.

Rao could explain that, to keep his increases equal in terms of percentage change, his allowance should increase by $75$ percent every two years.

Rao could explain that $$3$ is not enough of an increase to keep him well$-$stocked in music downloads.

Rao could explain that all of his friends are getting $$12$ per week, and it's only fair that he should, too.