Question 922361
Let x and y be the present ages of dorothy and dorilyn.
  so x+y= 41
 In 5 years dorothy will be twice as old as dorilyn
    so,  x+5 = 2*(y+5)
         x+5 =2*y+2*5
            x+5 = 2y+10
             move 5 to the right
                  x=2y+10-5
                   x=2y+5
          keep this x=2y+5 in x+y= 41
                             (2y+5)+y= 41
                                 3y+5 =41
                              subtract 5 on both sides
                                3y+5 -5 =41-5
                                  3y = 36
                              divide with 3 on both sides
                                   3y/3 = 36/3
                                  y= 12
                           x= 2y+5 
                             =2*12+5
                            =29
so dorothy & dorilyn's  present ages  are  29 years & 12 years
 after 3 years dorothy age will be  29+3 = 32 years
   after 3 years dorilyn's age will be 12+3 =15 years