Please help me with this question, please answer with details and explanation, I have the final value of the answer but

[answerhappygod]

Please help me with this question, please answer with
details and explanation, I have the final value of the answer but I
don't know how to solve it. The value ( answer ) is 1,9 x 10-16 M.
This is about photochemistry in chemical dynamics:
The hydroxyl radical reacts with methanol at a rate constant of
1.0 x 108 M-1 s-1. An aqueous solution containing 300 mM MeOH is
irradiated at a dose rate of 2 x 10-2 Gy s-1. Determine the
steady-state content of hydroxyl radicals (the G-value for OH is
0.28 μmol J-1)