A question-and-answer system providing an appropriate answer for a vehicle- related FAQ by using deep learning, and corresponding method are provided. The question-and-answer system includes: a memory that stores a plurality of representative questions to match a plurality of answers corresponding to the plurality of representative questions, respectively; a learning module configured to output a representative question corresponding to an input sentence from among the stored plurality of representative questions; and an output module configured to search the memory or an answer that matches the output representative question and output the found answer. The learning module is configured to perform multi task learning using a plurality of extended sentences for the plurality of representative questions as input data, and using the plurality of representative questions corresponding to the plurality of extended sentences, respectively, and a plurality of categories to which the plurality of extended sentences belong, respectively, as output data.