Question

if s= 2x+t over r then x equals

Answer 1

\[s=\frac{ 2x+t }{ r }\]is this what you mean:

Answer 2

if so, it is very simple. multiply everything by r like so...

\[r \left( s \right)=\left( \frac{ 2x+t }{ r } \right)r\]

rs=2x+t, now subtract t from both sides

rs-t= 2x, now divide by 2 on both sides

\[x=\frac{ rs-t }{ 2 }\]