With the original equation of s = 3/(t - 3), we must first multiply both sides by t-3. This gets us to (t - 3)(s) = 3, after which me must divide both sides by s, which gets us to t - 3 = 3/s. Finally, we must add 3 to both sides, which gets us answer of t = (3/s) + 3.
Hope this helps!
