Question

In a farm, both men and women were working. Exactly one- third of the staff brought one child each. One day, each male employee planted 13 trees and each women employee planted 10 trees and each child planted 6 trees. A total of 159 trees were planted on that day. How many women employees were there in that farm?

Answer 1

If there were m men and w women, then
13m+10w+6(m+w)/3 = 159
or
15m+12w = 159
5m+4w = 53
If that's all you know, then there are two solutions:
1 man and 12 women
5 men and 7 women