Please show code for what you have already tried!
(Or is the question a homework problem you're asking us to do for you?)
Have you already tried something simpler, such as applying Euler's Method?
And why do you want to use Runge-Kutta here to get a numerical solution since you already know an exact solution—which you could find in Mathematica from:
DSolve[{x'[t] == -x[t] + t^(1/10) (11/10 + t), x[0] == 0}, x[t], t]
