In a survey of 200 students of a College it was found that 120 had laptop, 90 had calculator and 70 had mobile phone, 40 had laptop and calculator,

In a survey of 200 students of a College it was found that 120 had laptop, 90 had calculator and 70 had mobile phone, 40 had laptop and calculator, 30 had calculator and mobile phone, 50 had mobile phone and laptop and 20 had none of these gadgets On the basis of above information answer the following questions.