## A1p2 hint

Suppse you had variables that contained the amount of income in each
bracket. It would then be easy to write an expression to calculate
the amount of tax. Now, you just need to figure out how to calculate
the values for those variables (without using `if`,
`cond`, or `case`).
Another hint: this problem can be done with procedures from the
Scheme handouts covered before this problem appears.