In an office, $30\%$ of the staff is female. $60\%$ of the female staff and $40\%$ of the male staff are married. The percentage of the unmarried staff in the office is:

Let the total number of staff in the office be $100$.
* Female staff = $30\%\text{ of }100=30$
* Male staff = $100-30=70$

Now, calculating the married staff:

* Married female staff = $60\%\text{ of }30=\frac{60}{100}\times 30=18$
* Married male staff = $40\%\text{ of }70=\frac{40}{100}\times 70=28$

Total married staff = $18+28=46$

Therefore, the total unmarried staff = $\text{Total staff}-\text{Total married staff}$

$$\text{Total unmarried staff}=100-46=54$$

Since the total staff is $100$, the percentage of unmarried staff is $54\%$.