Answer:
20.2 %
Explanation:
A typical high-income household in 1980 earned $140,397.
A similar household in 2009 earned $168,727.
We need to find the relative increase in income for these households from 1980 to 2009.
It can be calculated as follows :
![\%=(168727-140397)/(140397)* 100\\\\=20.17\%\\\\=20.2\%](https://img.qammunity.org/2022/formulas/mathematics/college/y6rw8nztoo5wjwxm9b25hsvs7rdva2r6r7.png)
So, the required percent is 20.2%.