Answer:
When it come to coordinates (x,y) x comes first then y. And when it comes to fractions rise/run rise is your numerator and run is your denominator.
y = 1/2x + b
3 = 1/2(4) + b
3 = 2 + b
1 = b
y = 1/2x + b
Hope this helps
your graph should look like this