I have a material science problem, I will thumbs up if solved quickly

Determine the carburizing time necessary to achieve a carbon concentration of 0.47wt% at a position 4.2mm into an iron-carbon alloy that initially contains 0.13wt%C. The surface concentration is to be maintained at 1.1wt%C, and the treatment is to be conducted at 1000C. Assume that D0=3.2105m2/s and Qd=121kJ/mol. The table Tabulation of Error Function Values may be useful. Part 1 * Review Equation 5.5 and determine the correct values for Cx,C0, and Cs Keep all these values in wt\%. Review your mathernatics. If you are having difficulty with this problem, you may wish to review: Solving Equations Equations, Symbols, and Units Powers and Roots From Equation 5.5 calculate the Gaussian error function: erf(2Dtx)=