Let the ages of P,Q and R be x,y and z yr, respectively. According to the question, x+2y+z‌‌=59 . . . (i) 3x+y+z‌‌=68 . . . (ii) x+3y+3z‌‌=108 . . . (iii) On multiplying Eq. (ii) by 3 and subtracting from Eq. (iii), we get 8x=96⇒x=12yr ∴ Age of P=12yr