Proportionality is when the two variables are related by a constant terms called the constant of proportionality, usually denoted as k. In this case, the variable is a constant multiple of the other variable. In equation, it is algebraically written as
y = kx
So, for the table showing values of x and y, we can solve for k.
When x=1 and y=3,
3 = k(1)
k = 3
When x = 2, and y = 6
6 = k(2)
k = 6/2
k = 3
When x= 3 and y=9
9 = k(3)
k = 9/3
k = 3
As you can observe, there is a constant term that relates the x and y variables. Therefore, the constant of proportionality for this relationship is 3.
