a+b+c=426 m stofa
b=a+19 m
c=a-4 m
a,b,c=?m
a+a+19+a-4=426
3a+19=426+4
3a+19=430
3a=430-19
3a=411
a=411:3 => a=137 m
b=137+19 => b=156 m
c=137-4 => c=133 m
Solutia: a=137m(primul balot); b=156m(al doilea balot); c=133m(al treilea balot)
Verificam: 137+156+133=426m