\(7^{25}:\left(7^{21}.46+7^{21}.3\right)=7^{25}:\left(49.7^{21}\right)=7^{25}:\left(7.7.7^{21}\right)=7^{25}:7^{23}=7^2=49\)
\(7^{25}:\left(7^{21}.46+7^{21}.3\right)\)
\(=7^{25}:\left[7^{21}\left(46+3\right)\right]\)
\(=7^{25}:\left(7^{21}.49\right)\)
\(=7^{25}:\left(7^{21}.7^2\right)\)
\(=7^{25}:7^{23}\)
\(=7^2\)
\(=49\)