For a fraction,\(\frac {a}{b}\)

\(\frac {a}{b}=\frac{a\times n}{b\times n}\)

 Where, n ≠ 0 

(i) We have to express \(\frac{-3}{5}\) as a rational number with denominator 20. 

In order to make the denominator 20, multiply 5 by 4. 

Therefore, 

\(\frac{-3}{5}=\frac{-3\times4}{5 \times 4}\)

\(\frac{-3}{5}=\frac{-12}{20}\)

(ii) We have to express \(\frac{-3}{5}\) as a rational number with denominator -30. 

In order to make the denominator -30, multiply 5 by -6. 

Therefore,

\(\frac{-3}{5}=\frac{-3\times-6}{5\times-6}\)

 \(\Rightarrow\)  \(\frac{-3}{5}=\frac{18}{-30}\)

 (iii) We have to express \(\frac{-3}{5}\) as a rational number with denominator 35. 

In order to make the denominator 35, multiply 5 by 7. 

Therefore,

\(\frac{-3}{5}=\frac{-3\times7}{5\times7}\)

\(\Rightarrow\) \(\frac{-3}{5}=\frac{-21}{35}\)

 (iv) We have to express\(\frac{-3}{5}\) as a rational number with denominator -40. 

In order to make the denominator 20, multiply 5 by -8. 

Therefore, 

\(\frac{-3}{5}=\frac{-3\times-8}{5\times-8}\)

\(\Rightarrow\) \(\frac{-3}{5}=\frac{24}{-40}\)