Răspuns :

x/y=4/9

x/4=y/9=k

x=4k
y=9k

3x+2y/5x +y=  3*4k+ 2*9k/5*4k + 9k=  12k + 9/10 + 9k=

= 21k +9/10=  21k+0,9
x/y=4/9 rezulta x=4y/9 si inlocuiesti in a doua relatie :
la numarator: 3*4y/9+2y=12y/9+18y/9=30y/9
la numitor: 5*4y/9+y=20y/9+9y/9=29y/9
Se reduc 9 si y si iti ramne: 30/29