x/2 = y/5 = z/11
x+y=28
x=28-y
x/2=y/5
28-y totul supra/2= y/5
28-y=y/5×2/1
28-y =2y/5
2y/5=28-y
2y=(28-y)×5
2y=28×5 -y×5
2y=140- 5y
2y+5y=140
7y=140
y=140:7
y=20
x=28-u
x=28-20
x=8
Probă
x/2=y/5
8/2=20/5
8/2=4
20/5=4 (adevarat )
daca y/5=z/11 =>
20/5=z/11
z/11=20/5
z=20/5 ×11/1
z=20×11 totul supra /5
z=220/5
z=44
Probă 44/11=4 =>(adevarat )
x/2 = y/5 = z/11
8/2=20/5=44/11
4=4=4 (adevarat )
