Question 1009989
I am not quite sure what you have: 
this
1. {{{4/5q+r=r+n}}}
or
2. {{{4/(5q+r)=r+n}}}


if you have 1. {{{4/5q+r=r+n}}}, then

{{{4/5q=r-r+n}}}

{{{4/5q=n}}}

{{{4=5nq}}}

{{{highlight(q=4/(5n))}}}


but, if you have 2. {{{4/(5q+r)=r+n}}}, then

{{{4=(r+n)(5q+r)}}}

{{{4/(r+n)=5q+r}}}

{{{4/(r+n)-r=5q}}}

{{{highlight(q=4/5(r+n)-r/5)}}}