Direction: Go through the passage given below and answer the question based on it.

In the class of 100 students each student has at least one pen of color Red, Blue and Black. Student having Red color pen does not have Blue color pen and vice versa. Number of student having Blue pen is 50 and 30 student has only Blue pen, student having Red pen is 20, 40 students have Black pen and 10 students have both Red and Black pen.