Explanation:
\(\frac{7}{10}\)
Let the required number be x.
Now,
\(1\frac{3}{4}\div\text{x}=2\frac{1}{2}\)
\(\Rightarrow\frac{7}{4}\times\frac{1}{\text{x}}=\frac{5}{2}\)
\(\Rightarrow\text{x}=\frac{7}{4}\times\frac{2}{5}\)
\(\Rightarrow\text{x}=\frac{7\times1}{2\times5}\)
\(\Rightarrow\text{x}=\frac{7}{10}\)
Thus, the required number is \(\frac{7}{10}\)