Given that segments RS and RT are tangent to circle Q, find the length of RS.

As they both are tangents of the same circle, their lengths must be equal.
RS = RT
x/4 = x-6.3
x = 4x - 25.2
4x-x = 25.2
3x = 25.2
x = 8.4
As, RS = x/4, it will be equal to 8.4/4 = 2.1
SO, YOUR FINAL ANSWER IS RS = 2.1