For the first part, assume it only goes right. Eg CH3CH2COOH + H2O -> CH3CH2COO- + H3O+ So on the left hand side of the equation, which compound is the B-L base and which is the acid? If you look at the right hand side, you can see that one of them has lost a proton, meaning its corresponding molecule on the left hand side is the B-L acid.