I really don't think you wrote the question properly. Or maybe you did, but this question doesn't make any sense! :/
Answer:
CD = 16.5
Step-by-step explanation:
To find the distance between two points, use this formula: 
point C can be info set 1: (10, -1) x₁ = 10 y₁ = -1
point D can be info set 2: (-6, 3) x₂ = -6 y₂ = 3
Substitute the information into the formula

Simplify inside each bracket
Square the numbers
Add inside the root
Enter into calculator
Rounded to the nearest tenth, the first decimal
The distance CD is 16.5.