Slope =
So taking 2 points (0,0) and (60,120)
we have slope = (120-0)/(60-0) = 120/60 = 2
general equation of linear graph is y=mx+b with m be the slope
so y=2x+b
Now to find b, just plug any point of the graph in, such as (0,0)
so we get something like 0=2(0) + b => b=0
So your equation is y=2x