Let the number of males be x.
Let the females be y.
x + y = 850 .............(a)
y - x = 60 .............(b)
The system of linear equations are represented as above.
Adding equations (a) and (b)
x + y + y - x = 850 +60
2y = 710
y =910/2 = 455
Recall: x + y = 850,
x + 455 = 850
x = 850 - 455
x = 395.
Number of males, x = 395
Number of females, y = 455
Hope this explains it.