[tex]y=\frac{1}{2}x+3 \parallel y=mx+b[/tex]
Two lines are parallel when their slopes are the same.
[tex]m=\frac{1}{2} \\ y=\frac{1}{2}x+b \\ \\ (2,5) \\ x=2 \\ y=5 \\ \Downarrow \\
5=\frac{1}{2} \times 2 + b \\ 5=1+b \\ b=4 \\ \\ \boxed{y=\frac{1}{2}x+4}
[/tex]