let us take any two points here (5,20) and (7,30)
now let us use slope formula to get its slope
![slope=(y2-y1)/(x2-x1)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/afx2qh6n5zql1loxl9237535sinfnup5d9.png)
![slope=(30-20)/(7-5)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/gkqc7bmtgu3jmzlv64ff16w6oz98up38k2.png)
slope =5
now let us use one coordinate (say (5,20)) and slope to get the y intercept
20= 5*5 +b
b=-5
plugging the values of b and m in the given equation we get
y=5x-5
or c=5m-5