In the figure below, and length units. If the equation of is , find the equation of .
For straight line graphs,
where is the slope and c is the -intercept.
Consider the equation of .
We can see that the slope is and the -intercept is 4.
If 2 lines are parallel, their slopes are equal. So, we know that the slope of is also .
cuts the -axis at which is 4 length units above 0, and cuts the -axis at which is 8 length units below .
Therefore, the -intercept of is .
Putting the values of slope and -intercept into gives us the equation of .