Answer 1

$\frac{5n-5-2n-2}{10n} = \frac{7n+7}{10n}$

Answer 2

$\frac{n-1}{2n}- \frac{n+1}{5n}= \frac{(n-1)5}{2n*5}- \frac{(n+1)2}{5n*2}= \frac{5n-5-2n-2}{10n}= \frac{3n-7}{10n}$