Tina  x hours
Louise 2x hours
Then you write an equation as you read the text
    x + 2x = 108  hours
Next you simplify and solve
      3x   = 108
       x   = 108/3 = 36.
ANSWER.  Tina worked 36 hours.   Louise worked  2*36 = 72 hours.
CHECK.   36 + 72 = 108  hours,  total combined time.    ! Correct !