My approach to this questions is as follows:
Given that the problem is asking us to find the ratio of the sum of two salaries which aren't defined in the problem we can start by defining some variables:
(1) Sum of salaries before the increase = Y
(2) Sum of the salaries after the increase = Z
(3) Number of employees BEFORE the increase = X
We are told in the question stem that the number of employees were reduced by 10%, so that means we will have (1-10/100)x employees remaining, or 9x/10.
Next we are told that the average salary AFTER the decrease is equal to 10% more of the original average. So we can set up the following question:
Y/(9x/10) = 11/10(Z/X), and simplying this further we have 10Y/9X = 11Z/10X. If you're stuck at this point you just need to realize that average salary is equal to $Sum of Total Salary / # of Employees.
Finally the question asks us for what percent of the July 1st salary sum of that BEFORE the decrease, or in other words we need to divide the July 1st Salaries by the BEFORE July 1st Salaries, which according to our variables are Y/Z.
So utilizing 10Y/9x = 11Z/10x we can conclude that Y/Z = 99/100, so 99% is the answer.