Please could you explain, in this problem the proportion of female and male revenues are given: 170000 and 68500 for year 2009. How these figures have been arrived at?
In 2008 there were no male clients – only female clients. So the revenue per female client is 200,000/8,000 = $25
The question says that the prices did not change. So the revenue from female clients in 2009 must have been 6,800 x $25 = $170,000. The rest of the revenue must have come from male clients.