25. The average of three numbers is 42. The first is twice the second and the second is twice the third. The difference between the largest and the smallest number is :

26. The average of the daily income of A, B and C is Rs. 60. If B earns Rs. 20 more than C and A earns double of what C earns; what is the daily income of C ?

27. The average of 6 observations is 12. A new seventh observation is included and the new average is decreased by 1. The seventh observation is :