290 students of MBA (International Business) in a reputed Business School have to study foreign language in Trimesters IV and V. Suppose the following information are given .
i. 120 students study Spanish
ii. 100 students study Mandarin
iii. At least 80 students, who study a foreign language, study neither Spanish nor Mandarin
Then the number of students who study Spanish but not Mandarin could be any number from

                                                                

It's given that 120 students study Spanish :         A + B = 120                                        ...(1)

              Also 100 students study Mandarin :       B + C = 100                                        ...(2)

At least 80 students will not opt for any of these two languages i.e.      

                                                     Spanish + Mandarin $$\leq$$ (290-80)

                                                     Spanish + Mandarin $$\leq$$ 210

                                                        A + B + C $$\leq$$ 210

Case 2: When B is minimum and A is maximum. 

Solving for boundary condition  A + B + C = 210                                                             ...(3)

Solving equations (1)+(2)-(3) 

                                                                   B = 10 

                                            i.e. A = 120 - B = 120 - 10 =110 {Maximum possible value of A}

Case 2: When B is maximum and A is minimum. 

Since B+C = 100 so, Maximum value B can attain is 100. Hence, the minimum value of A = 120 - B = 120 - 100 = 20 {Minimum possible value of A}

So we can say that the number of students who study Spanish but not Mandarin will be A [20 ,110].