The first thing you should do is use the variables to model the total number of employees at the company. We already know there are k male employees, so that's all set. How can we represent the number of female employees with the variables we're given? Since there are n more male employees than female employees, the number of female employees can be represented by the expression (k - n). This means that the total number of employees is: k + (k-n) = 2k - n.
Now, let's look back at the original question. We want an expression that represents the fraction of the employees that are male. Since there are k male employees at the company, and there are 2k - n total employees, the fraction we're looking for is k/(2k - n). Choice c is the correct answer!