Since you know the left side, you can set up an equality:
[tex] \frac{16}{8} = \frac{x}{10} [/tex]
This must be true because of some Triangle Theorem I don't remember, lol. But, then you can just solve for x (I cross multiplied):
[tex] \frac{16}{8} = \frac{x}{10} [/tex]
[tex]160=8x[/tex]
Simplify:
[tex]x = \frac{160}{8} = 20[/tex]
So, the answer is D. You can use many other ways too. But this is a clear way that your teacher probably taught you.
