a + b + c = 960
a + b = 53
b + c = 74
c = 960 - 53
c = 907
b = 74 - 907
b = - 833
a = 53 - ( - 833 )
a = 886
a+b+c=960
a+b=53
b+c=74
c=960-53
c=907
a=960-74
a=886
b=960-907-886
b= -833
Verificare:
907+886+(-833)=
1793-883
=960
Succes!
