Farmer Perry has 4 rabbits. The mass of Rabbit N is the same as the average mass of the 4 rabbits. Rabbit P weighs 8 kg less than the average mass of the 4 rabbits. The mass of Rabbit Q is 10 kg more than the average mass of the 4 rabbits. The mass of Rabbit R is 6 kg. Find the total mass of the 4 rabbits.
Let 1 u be the average mass of each rabbit.

Total mass of 4 rabbits
= 4 x 1 u
= 4 u

Mass of Rabbit N = 1 u
Mass of Rabbit P = 1 u - 8
Mass of Rabbit Q = 1 u + 10
Mass of Rabbit R = 6 kg

Total mass of the 4 rabbits
= 1 u + (1 u - 8) + (1 u + 10) + 6 
= 3 u - 8 + 10 + 6
= 3 u + 8

4 u = 3 u + 8
4 u - 3 u = 8

1 u = 8

Total mass of the 4 rabbits
= 4 u
= 4 x 8
= 32 kg

Answer(s): 32 kg