Question: if y=3x what is the constant of proportionality between y and x?
Answer: y results from something being multiplied by x , and the values are always proportional to one another. Notice that putting these points into a ratio of x-value to y-value results in 1:3 as a simplified version. So, the constant of proportionality is what x is being multiplied by to get y . In this case, it is 3 .