From the question, we know that 55 people pass at least one of chinese or English
So to find the total number of people who pass two subjects, we have
(32 + 42) - 55
= 19
The number (32 + 42) counts the number of people who pass either English or Chinese, however, it may happen that counts may repeat in case some people who pass both subjects, so we subtract the total number of people involved in passing subjects (i.e. 55), we could find the number of people who are double-counted, which represents the people who pass two subjects