A solution of A is mixed with an equal volume of a solution of B containing the same number of moles, and the reaction A + B → C occurs. At the end of 1 h, A is 75% reacted. How much of A will be left...

A solution of A is mixed with an equal volume of a solution of B containing the same number of moles, and the reaction A + B → C occurs. At the end of 1 h, A is 75% reacted. How much of A will be left unreacted at the end of 2 h if the reaction is (a) first order in A and zero order in B; (b) first order in both A and B; (c) zero order in both A and B?