Question 1131129
{{{1/10+1/n=1/4}}}

{{{1/4-1/10=1/n}}}

{{{10/40-4/40=1/n}}}

{{{6/40=1/n}}}

{{{3/20=1/n}}}


{{{n=20/3}}}


{{{highlight(6&2/3)}}}{{{hours}}}