There can be 2 answers depending the proportionality between y and x
Assuming y is directly proportional to x
[tex]y=kx[/tex] where k is constant of proportionality
[tex]8=20k[/tex]
[tex]k=\frac{8}{20}=\frac{2}{5}[/tex]
[tex]y=\frac{2}{5}x[/tex]
[tex]y=\frac{2}{5}*10[/tex]
[tex]y=4[/tex]
Assuming y is indirectly proportional to x
[tex]y=\frac{k}{x}[/tex] where k is constant of proportionality
[tex]8=\frac{k}{20}[/tex]
[tex]k=160[/tex]
[tex]y=\frac{160}{x}[/tex]
[tex]y=\frac{160}{10}[/tex]
[tex]y=16[/tex]
