If you are looking solve for s:
First, multiply each side of the equation by color(red)(t) to isolate the s term while keeping the equation balanced:
r * color(red)(t) = sqrt(s)/t * color(red)(t)
rt = sqrt(s)/color(red)(cancel(color(black)(t))) * cancel(color(red)(t))
rt = sqrt(s)
Now, square both sides of the equation to solve for s while keeping the equation balanced:
(rt)^2 = (sqrt(s))^2
r^2t^2 = s
s = r^2t^2
If you are looking solve for t:
Multiply both sides of the equation by color(red)(t)/color(blue)(r) to solve for t while keeping the equation balanced:
r * color(red)(t)/color(blue)(r) = sqrt(s)/t * color(red)(t)/color(blue)(r)
color(blue)(cancel(color(black)(r))) * color(red)(t)/cancel(color(blue)(r)) = sqrt(s)/color(red)(cancel(color(black)(t))) * cancel(color(red)(t))/color(blue)(r)
t = sqrt(s)/r
