(a+b)/(a-b) = 5/6; => a = -11b;
(20/100)*a = 4 +(30/100)*b; => (1/5)*a = 4 +(3/10)*b => 2a = 40 + 3b;
Inlocuim => -22b = 40 + 3b => b = -8/5 => a = 88/5;
Obs. In multimea numerelor rationale problema are solutia de mai sus iar in multimea numerelor intregi problema nu are solutie!
Bafta!