Two angles are said to be supplementary if the sum of their measures is 180 degrees.
Given that angles 25 and 26 are supplementary,
[tex]\angle25+\angle26=180[/tex]Also it is given that the angle 25 measures 124 degrees.
Substitute the value,
[tex]\begin{gathered} 124+\angle26=180 \\ \angle26=180-124 \\ \angle26=56 \end{gathered}[/tex]Thus, the angle 26 measures 56 degrees.