Hello, can you show me the steps to solve this problem using the correct rate law and explain why the answer is what is? I know the answer is 26 min, but I don't quite understand the concept. I will be sure to leave good review. Thanks in advance.

The half-life of a first-order reaction is 13 min. If the initial concentration of reactant is 0.085M it takes_______ min for it to decrease to 0.021M.