Question 1029037
The total salary is mean* number or 80*5500=440,000
10 workers get 5100, so that is 51,000 removed
the other 70 get one of two salaries
x+y=70; x gets 5400, y gets 5700
5400x+5700y=389,000, or what is left over.
54x+57y=3890
x+y=70
-54x-57y=-3890, negating everything
54x+54y=3780, multiplying the first by 54.  Now we can add them
-3y=-110
This doesn't give an integer.
50 can't be the right answer:
10@5100=51,000 total
50@5700=285,000 total
20@5400=108,000 total
That adds to 444,000, not 440,000
If the average salary were 5550 the answer would be 50.  As it stands here, there is no integer answer.