Question 919807

     let x- dina's age
        2x- michelle's age; note that dina is half as old as michelle
       x+3- juliet' age; note that dina is 3 years younger than juliet
     we have defined their ages 
       the sum of their ages is 39:
       x+2x+x+3=39 
     simplify then solve for x
     x=9-age of dina
     2x=18-age of michelle
     x+3=12-age of juliet
     checking: 9+18+12=39