Given data:
The distance hiked on monday =15.4 miles.
The distance hiked on Tuesday =20.6 miles.
The length of trail = 50 miles.
The distance hiked on Wednesday =m.
The equation can be written as,
[tex]15.4+20.6+m=50[/tex]Solving the above equation,
[tex]\begin{gathered} 36+m=50 \\ m=14 \end{gathered}[/tex]Thus, the required value of m is 14 miles.