The ratio of men to women working for a company 3 to 5 . if there are 51 men working for the company, what is the total number of employees?

There are numerous information's already given in the question. Based on those information's the answer can be easily deduced.

Ratio of men to women = 3 : 5
Total number of men = 51
Now
Men/Women = 3/5
51/women = 3/5
3 Women =51 * 5
3 Women = 255
Women = 255/3
             = 85
Then
Total number of employees = 51 + 85
                                            = 136
From the above deduction, it can be concluded that the total number of employees in the company is 136. I hope the procedure is clear enough for you to understand. 

The scale factor of what ?