Answer:
D (-4, -9)
Explanation:
midpoint formula:
(x₁ + x₂) / 2 , (y₁ + y₂) / 2
plug in C (2,7)
(2 + x₂) / 2 , (7 + y₂ ) / 2 = (-1, -1)
(2 + x₂) / 2 = -1
multiply each side by 2
2 + x₂ = -2
subtract 2 from both sides
x₂ = -4
(7 + y₂) / 2 = -1
multiply each side by 2
7 + y₂ = -2
subtract 7 from both sides
y₂ = -9
D (-4, -9)