please help, I am so confused

Answer:
[tex]\huge\boxed{25.2\ m}[/tex]
Step-by-step explanation:
In order to find the length of the missing side here, we must note that these triangles are similar.
Therefore their lengths are proportionate to each other.
So,
[tex]\frac{27.6}{11.5} = \frac{x}{10.5}[/tex]
We can solve for x by cross multiplying.
[tex]10.5\cdot 27.6 = 289.8\\\\289.8 \div 11.5 = 25.2[/tex]
Hope this helped!