Răspuns :
daca i mai mic ca u cu 5 asta imseamna ca u=i-5
inlocuim in ecuatie i+(i-5)=31=>i+i-5=31=>
=>2i=36=> i= 36:2=> i= 18
u= 18-5=> u= 13
inlocuim in ecuatie i+(i-5)=31=>i+i-5=31=>
=>2i=36=> i= 36:2=> i= 18
u= 18-5=> u= 13