Question 552736
It's very straightforward:
If the whole distance is {{{5}}} miles and he has gone is {{{3}}}{{{3/4}}}miles, the you would subtract the distance travelled ({{{3}}}{{{3/4}}}miles) from the whole distance ({{{5}}}miles) to get:
{{{5}}}-{{{3}}}{{{3/4}}} = {{{1}}}{{{1/4}}}miles.