The quantities xxx and yyy are proportional.
xxx yyy
151515 555
252525 8\dfrac{1}{3}8
3
1
​
8, start fraction, 1, divided by, 3, end fraction
3 1

Find the constant of proportionality (r)(r)left parenthesis, r, right parenthesis in the equation y=rxy=rxy, equals, r, x.