[tex]m=\frac{y_1-y_2}{x_1-x_2}[/tex]
Line 1:
[tex]m=\frac{5-3}{1-0}\\ m=\frac{2}{1}\\ m=2\\\\
\hbox{Point (0,3) is y-intercept so } b=3\\\\ y=2x+3[/tex]
Line 2:
[tex]m=\frac{1-(-1)}{-1-(-2)}\\
m=\frac{2}{1}\\
m=2\\\\
1=2\cdot(-1)+b\\
1=-2+b\\
b=3\\\\
y=2x+3[/tex]