The main problem with these questions is people panic and try to remember a formula/method from a maths lesson and unfortunately misremember it and/or use the wrong method. It's just counting really and not some form of quadratic or simultaneous equation.
Prudie's method is the best but if you are not sure of the method/ rules for solving ratio and piechart and similar problems then drawing/sketching a diagram and then repeatedly putting numbers into the two parts of the pie chart can help.
There is always the long method of solving these until you feel totally confident with an efficient method. Do a table with 3 columns: Men Women Difference. You can add a total column if you want.
On the first row write 130 (men), 230 (women), 100 (diff).
Then on the next row write 260, 460, 200
Then on the next row write 390, 690, 300.
Then on the next row write 520, 920, 400
At this point you might realise you are one seventh of the way there so just multiply everything by 7.
Alternatively, continue until the difference gets to 2800, then add together the number of men and women. It will need 28 rows but the effort can be worth it as you may soon see short cuts for future problems.
A spreadsheet could help too