We will have the following:
First, the probability of getting the first t-shirt white will be:
[tex]p_1=\frac{4}{9}[/tex]And the probability of getting the second t-shirt white will be:
[tex]p_2=\frac{3}{8}[/tex]Now, the probability of getting the two white t-shirts one after the other will be:
[tex]\begin{gathered} p_3=p_1\ast p_2\Rightarrow p_3=\frac{4}{9}\ast\frac{3}{8} \\ \\ \Rightarrow p_3=\frac{1}{6} \end{gathered}[/tex]So, the probability of getting the two white t-shirts one after the other is 1/6.