Answer:
b = 2
Step-by-step explanation:
Using the midpoint formula
(2, 1) = [ [tex]\frac{1}{2}[/tex](- 4 + 8), [tex]\frac{1}{2}[/tex](b + 0) ]
considering the y-coordinate, then
[tex]\frac{1}{2}[/tex] b = 1 ( multiply both sides by 2 )
⇒ b = 2
