Two points on the line are (0, 0) and (6, 9)
The slope of the line including them is the change in y over the change in x
m = (9 - 0) / (6 - 0)
m = 1.5
y = 1.5x + b
because the origin is one of the points on the line, the y intercept is zero
b = 0
so the line equation is
y = 1.5x
