Why is 5x = 8y (x ≠ 0), then y and X are proportional? I don't know how it's proportional,

Why is 5x = 8y (x ≠ 0), then y and X are proportional? I don't know how it's proportional,

5x=8y(x≠0),
y/x=(5/8) (x≠0),
Y / x = K (K ≠ 0), which means that y is proportional to X