The question does not seem complete, but I'll represent the statement mathematically and look for their ages each. This is because the worst they can ask for is their ages.
Let C stand for Courtney's age, A for Andrei's age, N for Natalie's age and S for Shari's age. From the question we can deduce the following:
C = 2A
C = N + 3
C = S/2
S - N = C + A
S = 2C, N = C - 3 and A = C/2, therefore we have
2C - (C - 3) = C + C/2
C + 3 = C + C/2
C/2 = 3 and C = 6
A = C/2
A= 6/2
A = 3
N = C - 3
N = 6 - 3
N = 3
S = 2C
S = 2 x 6
S = 12.
C = 6, A = 3, N = 3 and S = 12
Answer:

Step-by-step explanation:

hope this helps
brainliest appreciated
good luck! have a nice day!
1) Midpoint : (7/2,1/2), Quadrant 1
2. Midpoint: (5,1/2), Quadrant 2
Hope this helps. Please mark brainliest if you can