Y- intercept formula= y=mx+b.
We have at least one pair of points, so we need to find slope, or m.
I am going to use rise/run.
Rise 2, runs 4. That's 2/4 or 1/2.
I am going to plug in the point (0,3)
3= .5*0+b (.5 * 0= 0)
3= b or the y-intercept
I hope this helped you! <3