There are three categories of jobs HR, CA and PA. The

Solution

Let the salary of students who got the jobs of HR, CA and PA categories are A, B and C respectively.  The average salary the student who got the job of HR and CA category = 20 lakh per annum i.e. (A+B)/2 = 20 lakh per annum therefore, A + B = 20  ×  2 = 40 lakh per annum……..(i) the average salary the student who got the job of CA and PA category = 40 lakh per annum i.e. (B+C)/2 = 40 lakh per annum therefore, B + C = 40  ×  2 = 80 lakh per annum………(ii) the average salary the student who got the job of PA and HR category = 30 lakh per annum i.e. (C+A)/2 = 30 lakh per annum therefore, C+ A = 30  ×  2 = 60 lakh per annum…………(iii) Adding (i), (ii) and (iii) 2(A+B+C) = 40 + 80 + 60 2(A+B+C) = 180 lakh per annum A+B+C = 90 lakh per annum Which means total salary of HR, CA and PA is equal to 90 lakh per annum Average salary of HR, CA and PA = (A+B+C)/3 = 90/3 = 30 lakh per annum