Question 51248
Write the equation in slope-intercept form: 
{{{y = mx+b}}} 
You are given the slope, m = 4, so you can write:
{{{y = 4x+b}}} Now you need to find the value of b, the y-intercept. This is easily done because you were also given a point (2, 8) through which the line passes. 
So you substitute the (x, y) of the given popint (2, 8) into the equation {{{y = 4x+b}}} and solve for b.
{{{8 = 4(2) + b}}} Simplify.
{{{8 = 8 + b}}} Subtract 8 from both sides of the equation.
{{{0 = b}}}  So b = 0. Now you can write the final equation of the line whose slope is 4 and which passes through the point (2, 8).

{{{y = 4x}}}

Just out of curiosity, let's see what that looks like on a graph:
{{{graph(300,200,-5,5,-5,10,4x)}}}