For this case we have that by definition, the point-slope equation of a line is given by:
![y = mx + b](https://img.qammunity.org/2020/formulas/mathematics/high-school/fc4cgm6covys37zv2opmmp9ps4jxyjepvh.png)
Where:
m: It's the slope
b: It is the cut-off point with the y axis
We have two points:
![(x_ {1}, y_ {1}): (- 5,7)\\(x_ {2}, y_ {2}): (- 4,0)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8xfa8usr99a8bbkt3xvy1zbeguw7sg1zfd.png)
We found the slope:
![m = \frac {y_ {2} -y_ {1}} {x_ {2} -x_ {1}} = \frac {0-7} {- 4 - (- 5)} = \frac {-7} {-4 + 5} = \frac {-7} {1} = - 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pwyh4kacomm1hwjn8yoyu3zpddyqjzrs9k.png)
Thus, the equation is of the form:
![y = -7x + b](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zkq97x7vc5lnnec77ih13dqytdn993kfzq.png)
We substitute one of the points and find "b":
![0 = -7 (-4) + b\\0 = 28 + b\\b = -28](https://img.qammunity.org/2020/formulas/mathematics/middle-school/g7ld70bemzrkw24cxmb2rvx86atl7890z5.png)
Finally, the equation is:
![y = -7x-28](https://img.qammunity.org/2020/formulas/mathematics/middle-school/146bmcw8kpkifjzpraatrevdgc7w88lh1w.png)
Answer:
![y = -7x-28](https://img.qammunity.org/2020/formulas/mathematics/middle-school/146bmcw8kpkifjzpraatrevdgc7w88lh1w.png)