Here is the question I am struggling with:

Equal volumes of two equimolar solutions of reactants A and B are mixed, and the reaction A + B --> C occurs. At the end of 1 hour, A is 90% reacted. How much of A will be left unreacted at the end of 2 hours if the reaction is:

a). First order in A and zero order in B

b). First order in A and first order in B

c). Zero order in both A and B

Now, I know that the equation to use for b) is (1/(b[A]_{0}-a_{0}))(ln(_{0}/[A]_{0})-ln(_{t}/[A]_{t}))=k*t. However, I wasn't given any concentrations or % concentrations for B, and only that A and B are equimolar. Also, that equation, as far as I understand, only works when both reactants are first order, so I have no idea where to even begin solving a) and c). Any help you can give me would be greatly appreciated! Thank you!