Question 441467
{{{7/10 + 1/5}}}....common denominator is {{{10}}}

={{{7/10 + 1*2/(5*2)}}}

={{{7/10 + 2/10}}}

={{{(7+2)/10}}}

={{{9/10}}}

   and 

{{{5/8 - 1/4}}} ....common denominator is {{{8}}}


={{{5/8 - 1*2/(4*2)}}} 

={{{5/8 - 2/8}}} 

={{{(5-2)/8 }}} 

={{{3/8 }}}