Farmer Ivan has 4 puppies. The mass of Puppy V is the same as the average mass of the 4 puppies. Puppy W weighs 3 kg less than the average mass of the 4 puppies. The mass of Puppy X is 10 kg more than the average mass of the 4 puppies. The mass of Puppy Y is 12 kg. Find the total mass of the 4 puppies.
Let 1 u be the average mass of each puppy.

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

Mass of Puppy V = 1 u
Mass of Puppy W = 1 u - 3
Mass of Puppy X = 1 u + 10
Mass of Puppy Y = 12 kg

Total mass of the 4 puppies
= 1 u + (1 u - 3) + (1 u + 10) + 12 
= 3 u - 3 + 10 + 12
= 3 u + 19

4 u = 3 u + 19
4 u - 3 u = 19

1 u = 19

Total mass of the 4 puppies
= 4 u
= 4 x 19
= 76 kg

Answer(s): 76 kg