Courtney is twice as old as Andre and three years older than Natalie. Courtney is half Shari's age. The difference between Shari's age and Natalie's age is the same as the sum of Courtney's age and Andre's age. The equation below represents their ages.

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