In a class of 250 students it was found that 140 took math 85 took psychology and 65 took both math and psychology how many students in the class took math or psychology?

Answer 1

N(math) + N(psych) - N(math AND psych) = N(math OR psych)
140+85-65 = N(math OR psych) = 160

(the 250 did not enter the picture unless you want to note that 90 took neither math nor psych )