Răspuns :
e=5o
e-28=o+28=>e=o+56
o+56=5o=>56=5o-o=>o=56:4=>o=14 lei are Oana
e=5x14=70 lei are Emanuel
e-28=o+28=>e=o+56
o+56=5o=>56=5o-o=>o=56:4=>o=14 lei are Oana
e=5x14=70 lei are Emanuel
28:2=14 lei are Oana
14x5=70 lei are Emanuel
Proba:
70-28=42
14+28=42
deci, daca iar da 28 de lei, ar avea suma egala 42 lei