The line that represents the relationship between "y" and "x" passes through the origin and the points (k,7) and (-81,-9)
Assuming that "y" varies directly with "x", we can express their relationship as:
![y=mx](https://img.qammunity.org/2023/formulas/mathematics/college/vvo9hzn6fevndvhvtnqpmjhwggazm06a.png)
Where "m" represents the slope of the line, also known as coefficient of proportionality or variation.
Using this expression and the known paired values (-81,-9) we can calculate the value of the slope as:
![\begin{gathered} -9=m(-81) \\ m=-(9)/(-81) \\ m=(1)/(9) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/icx3ih98hpg05gxxng6d05hoa4y3k4fgm6.png)
The slope of the line is m=1/9 → this value is constant, regardless the values of x and y. Using it you can determine the value of k as follows:
![\begin{gathered} y=(1)/(9)x \\ \text{For (k,7)} \\ 7=(1)/(9)k \\ k=(7)/((1)/(9)) \\ k=7\cdot9 \\ k=63 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/m4ds2i8x63e9qtgovcz6fspfhq8xqth0un.png)
The value of k is 63