Answer:
An explicit expression is equal to 3m/8
Step-by-step explanation:
we know that
Function T gives the time the Hobbits have to prepare for the attack, T(k), in minutes, as a function of troll's distance, k, in meters
so
![T(k)=\frac{k}{80}](https://tex.z-dn.net/?f=T%28k%29%3D%5Cfrac%7Bk%7D%7B80%7D)
Function V gives visibility from the watchtower, V(m), in meters, as a function of the height of the watchtower, m, in meters
so
![V(m)=50m](https://tex.z-dn.net/?f=V%28m%29%3D50m)
Find the composite figure ![T(V(m))](https://tex.z-dn.net/?f=T%28V%28m%29%29)
That will give the time the Hobbits have to prepare for the troll attack as a function of the height, m, of the watchtower
Substitute the variable k in the function T by the function V(m)
![T(V(m))=\frac{50m}{80}](https://tex.z-dn.net/?f=T%28V%28m%29%29%3D%5Cfrac%7B50m%7D%7B80%7D)
simplify
![T(V(m))=\frac{5m}{8}](https://tex.z-dn.net/?f=T%28V%28m%29%29%3D%5Cfrac%7B5m%7D%7B8%7D)
therefore
An explicit expression is equal to 3m/8