Calculate the ratio of acid to dissociated ion when pH=2.00 and the Ka= 2.75 x 10^-5?

chemistry question: Acetylsalicylic acid (aspirin) can have a serious effect on the stomach. Only the undissociated acid can cross the stomach lining. Calculate the ratio of acid to dissociated ion when the pH of the stomach is 2.00. The Ka of this acid is 2.75 x 10^ -5.