1)
2ab+3ba=577
Notam cu k numerele a si b
a+b(2+3)=577
a+b*5=577
5a+5b=577
k+k=577-5
2k=572/2
k=286
Verificare
286*2+5=577
4)
a+b+c=8511
a=1266+b
b=2055-c
Notam cu k pe a+b+c
3k=8511
k=8511 impartit la 3
k=2837
a=1266+2837
a=4103
b=c+2055
b=4103-1266
b=2837
4103+2837+c=8511
6920+c=8511
c=8511-6920
c=1571
Verificare
4103+2837+1571=8511