The state income tax where Kristin lives is levied at the rate of p%

Let p=0. implying the following:

Percentage for the first $28000 = p = 0%
Percentage for the remaining amount = p+2 = 2%
Percentage for the MIXTURE of the two amounts = p+0.25 = 0.25%

Let F = the first $28000 and R = the remaining amount.
The following approach is called ALLIGATION -- a very efficient way to handle MIXTURE PROBLEMS.

Step 1: Plot the 3 percentages on a number line, with the percentages for F and R on the ends and the percentage for the mixture in the middle.
F 0%-------------0.25%------------2% R

Step 2: Calculate the distances between the percentages.
F 0%-----0.25-----0.25%-----1.75-----2% R

Step 3: Determine the ratio for the mixture.
The ratio of F to R is equal to the RECIPROCAL of the distances in red.
F:R = 1.75 : 0.25 = 175:25 = 7:1

The sum of the parts of the ratio = 7+1 = 8
Implication:
Of every $8 of income, F constitutes $7 and R constitutes $1, with the result that F ($28000) must be equal to 7/8 of the total income:
\(28000 = \frac{7}{8}x\)
\(28000*8 = 7x\)
\(4000*8 = x\)
\(x = 32000\)