Question

Trei baloturi de stofa au impreuna 120 m.Primele doua au impreuna 67 m,iar al doilea este cu 7 m mai mare decat al treilea.Cati m de stofa are primul balon?

Answer 1

a+b+c=120cm
a+b=67
67+c=120
c=120-67=53
b=53+7=60
a=120-(60+53)=120-113=7m

Answer 2

$x+y+z=120 \\ x+y=67 \\ z=120-67 \\ \boxed{z=53} \\ y=7+z \\ y=53+7 \\ \boxed{y=60} \\ x=120-(53+60) \\ x=120-113 \\ \boxed{x=7}.$