Răspuns:
a)
a+b-c= 1200
a+b= 650
(a+b-c)- (a+b) = 1200-650 = 550
=> -c=550 => c=-550
b-c=250
=>b-(-550)=250
=> b+550 = 250|-550 => b=-300
a=650-b = 650-(-300)=850
b)
a+b-c=900
a+b=450
b-c=800
(a+b-c)-(b-c)=900-800=100
=>a=100 => b=450-100=350
350-c=800 =>c=350-800= -450
