Since the slope of a line is 
And 2 points of the line are given, (4,5) and (8,y) we can substitute those values into our equation.
Since the slope of the line is 3,
Multiplying both sides by 4 would give us:
y-5=12
y=17
Therefore the missing y value equals 17.
And 2 points of the line are given, (4,5) and (8,y) we can substitute those values into our equation.
Since the slope of the line is 3,
Multiplying both sides by 4 would give us:
y-5=12
y=17
Therefore the missing y value equals 17.