Step 1: Quoting the theorem of a straight line
The theorem of a straight line says Total angles on a straight line is equal to 180°.
Step 2:
m<16 and m<15 are angles on a straight line from the diagram given,
[tex]\begin{gathered} \text{where} \\ m<16=139^0 \\ m<15=\text{?} \\ \text{therefore,} \\ m<16+m<15=180^0 \\ 139^0+m<15=180^0 \\ \text{Collecting like terms} \\ m<15=180^0-139^0 \\ m<15=41^0 \end{gathered}[/tex]Hence the value of m<15= 41°.