Răspuns:
x × 5 = y × 6 = z × 15 = K (constanta)
==> x = K/5; y= K/6; z= K/15
==> 3x-2y-z = 3K/5 - 2K/6 - K/15 = 12 / × 30
==> 30×3K/15 - 30×2K/6 - 30K/15 = 360
==> 6×3K - 5×2K - 2K = 360
==> 18K - 10K - 2k = 360
==> 6K = 360/:6 ==> K = 60
==> x= 60/5 = 12;
y= 60/6 = 10;
z=60/15 = 4