Let the unknown number be x.
80% of x is 140. This is written to be:
[tex]\frac{80}{100}\times x=140[/tex]We can solve for x as follows:
Multiply both sides by 100:
[tex]80x=14000[/tex]Divide both sides by 80:
[tex]\begin{gathered} x=\frac{14000}{80} \\ x=175 \end{gathered}[/tex]The number is 175.