Given,
Increase rate of population of town = \(\frac{40}{1000}\times100\) = 4% annually
Present population of town = 175760
Let population of town 3 years ago was = X
So,
\(= x({1}+\frac{4}{100})({1}+\frac{4}{100})({1}+\frac{4}{100})\) = 175760
\(=x\times\frac{26}{25}\times\frac{26}{25}\times\frac{26}{25}\) = 175760
\(= x = \frac{(175760 \times 25 \times 25 \times 25)}{26\times 26 \times 26}\) = 156250
Hence,
Population of town 3 years ago was = 156250