The cleaned desks is 40%.
Given:
Total number of desks is, N = 3500.
Number of desks cleaned is, C = 1400.
The objective is to find the percentage of cleaned desks.
Consider the percentage as x.
Then, the equation can be represented as,
![\begin{gathered} (x)/(100)\cdot3500=1400 \\ (x)/(100)=(1400)/(3500) \\ x=(14)/(35)\cdot100 \\ x=40 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/6qvyd25650d0pzz6g533sjovvco26mfq30.png)
Hence, the percentage of cleaned desks is 40%.