103. Solving a chemistry problem

21-7. One of the methods for estimating the age of biological objects is based on measuring the content of optical isomers of amino acids in them. In living organisms, the ratio of concentrations of D- and L-isomers is constant ([D]o/[L]o = a). In dead organisms, racemization occurs: L↔D “(At the top and bottom under the double arrows, the letter “k” is located, I could not adequately depict it there, therefore this footnote appeared)”.
What is the age of a biological object in which [D] / [L] = b? Solve the problem in general form for the sample containing aspartic acid (k = 1.48*10-5 years-1, a = 0.07, b = 0.27).