[tex]\begin{gathered} \text{ The equation of a line that passes trough two points (x1,y1) and (x2,y2) is} \\ y=mx+b \\ \text{where} \\ m=\frac{y_2-y_1}{x_2-x_1} \end{gathered}[/tex][tex]\begin{gathered} \text{thus } \\ m=\frac{1-5}{-5-0} \\ m=\frac{-4}{-5} \\ m=\frac{4}{5} \end{gathered}[/tex][tex]\begin{gathered} \text{ the equation is now} \\ y=\frac{4}{5}x+b \\ \text{now, if we replace the point (0,5) x=0, y=5, then the value of b is} \\ 5=\frac{4}{5}(0)+b \\ 5=0+b \\ 5=b \\ \\ \text{and the equation is now} \\ y=\frac{4}{5}x+5 \end{gathered}[/tex]
