First find the slope.
Get 2 points and use the slope formula.
(0,4)(1,2)
2-4 / 1-0
-2 / -1 = 2
y = 2x + b
Now to find the y - intercept
The point where x is 0 and y is a number is your y - intercept. In this case it’s the first point. (0,4)
The equation in y=mx + b form would be....
y = 2x + 4
Hope I helped:) if you have any questions comment so I can help.