I---------I---------I---------I---------I 4x
I---------I 13 I x+13
58-13=45
45:5=9
4x=4*9=36 l in bidon 1
58-36=22 l in bidon 2
prin ecuatie
x=cantitatea din bidon 1
x/4+13= cantitatea bidon 2
x+x/4+13=58
x+x/4=45
4x+x=180
5x=180
x=36 l in bidon 1
x/4+13=36/4+13=9+13=22 l in bidon 2