Let's begin.
The equation of a line is like : [tex]y=mx+p[/tex]
You must know that two parallel lines have the same slope, so here the slope will be [tex]m= \frac{1}{2} [/tex].
Now we have the "m".
We just have to write an equation in order to find the letter "p".
Here we have :
[tex]y=-5
[/tex]
[tex]x=10[/tex]
Therefore :
[tex]y=mx+p[/tex]
[tex]-5= \frac{1}{2}*10+p [/tex]
[tex]-5=5+p[/tex]
[tex]-5-5=p[/tex]
[tex]-10=p[/tex]
In short, the answer would be D) [tex]y= \frac{1}{2} x-10[/tex]
Hope this helps !
Photon