<u>Given</u>:
Let x represents the number of weeks.
Let y represents the amount of money.
Given that you are saving money for a new cell phone.
At week 0 you have saved $20 and at week 10 you have $100.
Writing this as coordinates, we get;
(0,20) and (10,100)
We need to determine the slope of the linear equation.
<u>Slope</u>:
The slope of the equation can be determined using the formula,
![m=\frac{y_2-y_1}{x_2-x_1}](https://tex.z-dn.net/?f=m%3D%5Cfrac%7By_2-y_1%7D%7Bx_2-x_1%7D)
Substituting the coordinates, we get;
![m=\frac{100-20}{10-0}](https://tex.z-dn.net/?f=m%3D%5Cfrac%7B100-20%7D%7B10-0%7D)
![m=\frac{80}{10}](https://tex.z-dn.net/?f=m%3D%5Cfrac%7B80%7D%7B10%7D)
![m=8](https://tex.z-dn.net/?f=m%3D8)
Thus, the slope of the linear equation is $8.
Hence, $8 is put away each week.