Shall I write the name of the method I've chosen?
Pepe Chapuzas asked this during a systems test. I suposed he meant elimination, substitution or equalization... but not... In his test there's no system...
In a farm there were rabbits and chickens. There were 62 heads and 168 legs. ¿How many rabbits and haw many chicken were there?
Pepe Chapuzas wrote this:
Method of the shoes: The farmer bought a pair of shoes to each animal...
There were 62 heads, that is, 62 animals.
There were 62 · 2 = 124 shoes.
There were 168 − 124 = 44 legs without shoes, that is, 44 rabbit hands.
There were 44 : 2 = 22 rabbits.
There were 62 − 22 = 40 chickens.