Răspuns:
Explicație pas cu pas:
a)x/3=y/8 => 8x=3y
x+y=22 => x=22-y
Din prima ecuatie: y=8x/3
Introducem y in a doua
x=22-8x/3 => 3x=66-8x => 11x=66 => x=6 => y=22-x=22-6=16
b)Idem acelasi rationament
x/y=4/9 => 9x=4y => y=9x/4
2x+3y=40 => y=(40-2x)/3
9x/4=(40-2x)/3 => 18x=4(40-2x) => 18x=160-8x => 10x=160 => x=16
y=9x/4=9*16/4=36
c)5x=3y => => y=5x/3
4y-3x=0,11 => y=(0,11-3x)/4 =>
5x/3=(0,11-3x)/4 => 20x=3(0,11-3x) => 20x=0,33-9x
29x=0,33 => x=29/0,33
y=5x/3=5*29/3*0,33=145/0,99
