Notam cu x castanele Mariei .
Andrei a adunat 1/2x
Ciprian a adunat 1/2 ( 1/2x)
Avem ecuatia :
x+ 1/2x + 1/2 (1/2x) = 91
x+1/2x + 1/4x=91
Amplificam :
4x+2x+x=364
7x=364
x=364/7
x=52 castane Maria
Andrei a adunat 26 de castane si Ciprian a adunat 13 castane .