Răspuns :
a+b=80 => a=80-b (1)
2xa-3xb=35 (2)
inlocuim (1) in (2)
2x(80-b)-3b=35
160-2b-3b=35
160-35=2b+3b
125=5b
b=125:5
b=25
a+b=80
a+25=80
a=80-25
a=55
2xa-3xb=35 (2)
inlocuim (1) in (2)
2x(80-b)-3b=35
160-2b-3b=35
160-35=2b+3b
125=5b
b=125:5
b=25
a+b=80
a+25=80
a=80-25
a=55