We have an average humidity of 79%.
It drops by 15% in the afternoon.
We consider that it decreases 15% of the original humidity of 79%. We don't substract the percentages directly.
We start by expressing both percentages as decimals: 79% will be 0.79 and 15% will be 0.15.
Then, we can calculate the humidity in the afternoon as:
![\begin{gathered} H_a=(1-0.15)H_(av) \\ H_a=0.85*H_(av) \\ H_a=0.85*0.79 \\ H_a=0.6715 \\ H_a=67.2\% \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ez7vqr8s8shyuank6e2j11s7emkn62rb02.png)
Answer: the humidity in the afternoon is 67.2%.