The Marginal Tax Rate is computed by:
Change in total tax paid
Divided by
Change in income
So in the problem:
21000 – 18400
Divided by
90000 – 80000
= 2600 / 10000
= 0.26, multiply this by 100% to get the percentage
= 26%
Average Tax Rate:
Total tax paid
Divided by
Income
= 21000 / 90000
= 0.2333333, multiply this by 100% to get the percentage
= 23.3%
Therefore, the answer is 26; 23.3.