Answer :
The given transformation of ratio is,
[tex]\frac{2}{10}\rightarrow\frac{4}{20}[/tex]That is, let x be the factor that was multiplied with the first fraction to get the second one. We can write,
[tex]\frac{2}{10}\times x=\frac{4}{20}[/tex]Thus, the value of x can be calculated as,
[tex]x=\frac{4}{20}\times\frac{10}{4}=2[/tex]Thus the answer is,
You can multiply both quantities in the ratio 2 to 10 by 2 to get the ratio 4 to 20.