Answer:
369 students have taken a course in either calculus or discrete mathematics
Step-by-step explanation:
I am going to build the Venn's diagram of these values.
I am going to say that:
A is the number of students who have taken a course in calculus.
B is the number of students who have taken a course in discrete mathematics.
We have that:

In which a is the number of students who have taken a course in calculus but not in discrete mathematics and
is the number of students who have taken a course in both calculus and discrete mathematics.
By the same logic, we have that:

188 who have taken courses in both calculus and discrete mathematics.
This means that 
212 who have taken a course in discrete mathematics
This means that 
345 students at a college who have taken a course in calculus
This means that 
How many students have taken a course in either calculus or discrete mathematics

369 students have taken a course in either calculus or discrete mathematics