Explicație pas cu pas:
Din egalitatea : 2x=3y= 2/3 luăm separat
{ 2x= 2/3 => {x=(2/3)/2
{3y= 2/3 {y=(2/3)/3
{x=2/3 × 1/2 => {x=2/6= 1/3
{y=2/3 × 1/3 {y=2/9
x+y/2x-y devine
1/3 +( 2/9) /(2/3) - 2/9=
1/3 +(2/9) × (3/2) -2/9=
1/3 + 6/18 -2/9 =
1/3 +3/9 -2/9=
1/3 +1/9
(3+1)/9 =4/9
