Proportional Relationship
Two variables x and y have a proportional relationship it the following equation stands:
y = kx
Where k is the constant of proportionality.
The number of tiles needed by Jack (y) has a proportional relationship with the length in feet of the hallway (x).
The table gives us some values. We'll summarize them as ordered pairs (x,y) as follows:
(3,27) (6,54) (7,63) (11,99)
We can use any of those ordered pairs to find the value of k. For example, (3,27). Substituting into the equation:
27 = k.3
Solving for k:
k= 27/3 = 9
Thus the equation is:
y = 9x
Note: We could have used any other ordered pair and we would have obtained the very same value of k.