Answer: B. (10, 50)
Step-by-step explanation:
y = 0.5(20x - [tex]x^{2}[/tex])
[tex]y=-\frac{1}{2} x^{2} + 10x[/tex]
to find x coord of vertex use the equation
[tex]\frac{-b}{2a}[/tex]
[tex]x=\frac{-10}{-1} \\\\x=10[/tex]
plug in x to the original equation
y = 0.5(20(10) - [tex](10)^{2}[/tex]
y = 0.5(100)
y = 50
Answer: (10, 50)