\[8\frac{9^{\backslash 5}}{40} - 6\frac{13^{\backslash 4}}{50} = 7\frac{49}{40} - 6\frac{13}{50} =\]
\[= 7\frac{245}{200} - 6\frac{52}{200} = 1\frac{193}{200}\]