The average salary per head of the entire staff of an office including the officers and clerks is Rs.90. The average salary per head of the officers is Rs.600 and that of the clerk is Rs.84. If the number of officers is 12, find the number of clerks in the office?
Let number of clerk be x.
Number of head officers = 12
total staff is 12+x
Average salary of entire staff = Rs. 90
Average salary of per head officer = Rs. 600
Total salary of 12 officer = 600 * 12 = Rs. 7200
Total salary of entire staff is (12+x)90
Average salary of clerk = Rs. 84
Total salary of clerks is x*84
then (12 + x )(90) = 7200 + 84x
not understand
Let number of clerk be x.
Number of head officers = 12
total staff is 12+x
Average salary of entire staff = Rs. 90
Average salary of per head officer = Rs. 600
Total salary of 12 officer = 600 * 12 = Rs. 7200
Total salary of entire staff is (12+x)90
Average salary of clerk = Rs. 84
Total salary of clerks is x*84
then (12 + x )(90) = 7200 + 84x
1080 + 90x = 7200 + 84x
6x = 6120
x = 1020