Let total number of units = x
As per the given data, 60% units constitutes 66 offices.
Hence,
[tex]0.6x=66[/tex]Solving further for x we have,
[tex]\begin{gathered} x=\frac{66}{0.6} \\ =\frac{660}{6} \\ =110 \end{gathered}[/tex]Thus, there are total number of 110 offices in a building.