Question 68656
Assuming your equation looks like this:

{{{s=x*sqrt(2*g)/(x+y)}}}

you can multiply both sides by (x+y)

{{{(x+y)*s=(x+y)*(x*sqrt(2*g))/(x+y)}}}

the x+y factor on the right hand side will cancel out leaving you with
{{{(x+y)*s=x*sqrt(2*g)}}}

Then, distribute the s among the (x+y) factor on the left hand side

{{{sx+sy=x*sqrt(2*g)}}}

move the sx term to the right by subtracting it from both sides

{{{sx-sx+sy=x*sqrt(2*g)-sx}}}

which wil leave you with

{{{sy=x*sqrt(2*g)-sx}}}

then finally divide both sides by s to isolate y

{{{y=(x*sqrt(2*g)-sx)/s}}}

which could also be expressed as

{{{y=(x*sqrt(2*g))/s-x}}}