first take 2 coordinate too find gradient .. you can try all the coordinate and you will get all same gradient .
so i take the coordinate (4,10) and (2,5)
you can choose any coordinate too.
then.
[tex]formula \: for \: gradient \: \\ m = \frac{y - y}{x - x} \\ m = \frac{10 - 5}{4 - 2} \\ m = \frac{5}{2} \\ fraction \: change \: to \: decimal \\ = 2.5 \\ next \: : \\ formula \: for \: equation \: to \: find \: c \: \\ y = mx + c \\ choose \: a \: coordinate \: = (2 \: 5) \: \\ 5 = 2.5 (2) + c \\ 5 = 5 + c \\ c = 0 \\ so \: the \: equation \: is \: y = 2.5x + 0 \\ thats \: mean \: the \: answer \: is \: c \: which \: is \: y = 2.5x[/tex]
