Question 900477
If you change everything to a common denominator, it's much easier.  Let's use 20ths.
{{{1/4}}}={{{5/20}}}
{{{1/10}}}={{{2/20}}}
{{{3/4}}}={{{15/20}}}
{{{9/10}}}={{{18/20}}}<br>Now your problem is {{{5/20}}}-{{{2/20}}} over {{{15/20}}}-{{{18/20}}}, or
{{{3/20}}}over{{{-3/20}}}
Cancel out the 20ths to get
{{{3/-3}}} which reduces to -1