y=mx + b (the slope-intercept formula)

(12) = 2(4) + b

solve for b and you get 4

So b, the y-intercept, is 4

and your final equation for the line becomes

y = 2x + 4

Hope that helps

Point (4,12) is the point X=4, Y=12. The Y intercept is at the point (0,?). Since the slope is 2 (in other words, Y increases by 2 for every X increase of 1), the Y value increases 8 for an increase of 4 for the X value. Imagine that as a change of (4,8). Subtracting (4,8) from (4,12) yields (0,4). Therefore, the Y intercept is 4 and the equation is Y=2X+4.

This is simple for me, since I’m a mathematician, but it’s really very basic. Linear equations are the connection between geometry and algebra, and the connections are sometimes the hardest things to understand.

Hope this helps.

but what you do is

y=mx+b

substitue your values

so

(4,12)

12=2(4) +b

12= 8+b

4=b

y=2x+4

y=2x+4