Total age of 3 sisters is 39

Question

Dina is 1/2 as old as Michelle and 3 years younger than Juliettte.
How old are the sisters ?

Answer 1

D+M+J=39
D=1/2 M
D=J+3

and, M=2D
J=D-3
intothe first equation
D+2D+D-3=39
4d=36
you take if from here.