Slope:-
[tex]\\ \sf\longmapsto m=\dfrac{30-20}{1}=10[/tex]
Now
equation in point slope form
[tex]\\ \sf\longmapsto y-20=10(x-2)[/tex]
[tex]\\ \sf\longmapsto y-20=10x-20[/tex]
[tex]\\ \sf\longmapsto y=10x[/tex]
Or
[tex]\\ \sf\longmapsto f(x)=10x[/tex]
