Answer:
2 is the constant of proportionality.
Step-by-step explanation:
When dealing with lines with y-intercepts, you often hear the term slope (rise over run) to distinguish the relationship between the y-variable and the x-variable. However, when dealing with lines that cross the origin, we're dealing with proportionality, not slope.
Since lines that cross the origin have the x-intercepts and y-intercepts of 0, there is no need to use the formula y= mx+b if there is no b. We instead use y=kx to plot proportional relationships, where k is the constant of proportionality.
So in this example, we have a proportional relationship. Luckily, we are given a ordered pair (2,4) to work with. When finding the constant of proportionality, it is as simple as substituting the x- and y-coordinates into the equation of y=kx because there is no y-intercept we need to worry about.
y =kx
(4) = k(2)
We then divide 2 on both sides to isolate the variable k.
2 = k
k = 2
We can now safely say that 2 is the constant of proportionality.
