Given $5$ boys and $4$ girls are in total

We can select $3$ boys from $5$ boys in \[\Rightarrow {{~}^{5}}{{C}_{3}}=\] ways

Similarly, we can select $3$ boys from $54$ girls in \[\Rightarrow {{~}^{4}}{{C}_{3}}=\] ways

∴ Number of ways a team of $3$ boys and $3$ girls can be selected is

\[^{5}{{C}_{3}}~\times {{~}^{4}}{{C}_{3}}\]

\[\Rightarrow {{~}^{5}}{{C}_{3}}~\times {{~}^{4}}{{C}_{3}}~=\]

\[\Rightarrow {{~}^{5}}{{C}_{3}}~\times {{~}^{4}}{{C}_{3}}~=~10~\times \text{ }4\text{ }=\text{ }40\]

∴ Number of ways a team of $3$ boys and $3$ girls can be selected is \[^{5}{{C}_{3}}~\times {{~}^{4}}{{C}_{3}}~=\text{ }40\text{ }ways\]