I looked at the step by step instructions and I still don’t understand how to solve this.

Given:
The point ( 10,3) and ( 6,31 ) are two anchor points on a trend line.
To find the equation of line passing through two points.
First find the slope of the line,
[tex]\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1} \\ (x_1,y_1)=(10,3) \\ (x_2,y_2)=(6,31) \\ m=\frac{31-3}{6-10} \\ m=\frac{28}{-4} \\ m=-7 \end{gathered}[/tex]Now, to find the y-intercept,
[tex]\begin{gathered} y=mx+b \\ \text{Here, b is y-intercept} \\ y=-7x+b \\ (x,y_{})=(10,3) \\ 3=-7(10)+b \\ 3=-70+b \\ 3+70=b \\ b=73 \end{gathered}[/tex]So, the equation of line is,
[tex]\begin{gathered} y=mx+b \\ y=-7x+73 \end{gathered}[/tex]Answer: y = -7x +73.