ANSWER
About 162 people
EXPLANATION
The first step is to find the probability that a randomly selected student from her school takes the subway.
The probability is given as:
[tex]P(subway)=\frac{n(\text{subway)}}{n(\text{total)}}[/tex]
Since 8 out of 20 people take the subway, we have that:
[tex]\begin{gathered} P(subway)=\frac{8}{20} \\ P(subway)=\frac{2}{5} \end{gathered}[/tex]
Now, to find the number of students expected to take the subway, multiply the total number of students in her school by the probability that one person takes the subway.
That is:
[tex]\begin{gathered} 406\cdot\frac{2}{5} \\ \Rightarrow162.4 \\ \approx162\text{ people} \end{gathered}[/tex]
Therefore, Destiny should expect about 162 people to take the subway.