Răspuns :
notam cele 3 nr date :a,b si c si x ac nr care este adunat si scazut
a=b+x
c=b-x
b=120
=>a=120+x
c=120-x
=> a+b+c=120+x+120+120-x=3*120=360
a=b+x
c=b-x
b=120
=>a=120+x
c=120-x
=> a+b+c=120+x+120+120-x=3*120=360
a+b+c=a+120+c
a=b+y
b=120
c=120-y
---------------------
a=?;b=? c=?
(a+y)+b+(c-y)=n
n=a+(b:2y)+c
y=120:2
y=60
a=b+y
a=120+60
a=180
b=120
c=b-y
c=120-60
c=60
a+b+c=n
180+120+60=360
n=360
a+b+c=360
a=b+y
b=120
c=120-y
---------------------
a=?;b=? c=?
(a+y)+b+(c-y)=n
n=a+(b:2y)+c
y=120:2
y=60
a=b+y
a=120+60
a=180
b=120
c=b-y
c=120-60
c=60
a+b+c=n
180+120+60=360
n=360
a+b+c=360