Since we have fixed the selection of Aditya, the grouping of the remaining people into 2 groups containing 3 members each can be done in $\frac{5!}{(2!\times 3!)}$ ways =10 ways

Now, if both Aditya and Dhan are selected, 2 out of the three members in a sub-team are already selected. The third person can be anyone of the remaining 4, which means that we have 4 different possibilities. Thus, the percent of all possible subteams that include Aditya, also include Dhan = $\frac{4}{10}=40\%$