Employees of a certain unit planted trees in the suburbs, and (1/3) of them each brought a child to participate. Each male employee planted 13 trees, each female employee planted 10 trees, and each child planted 6 trees. They planted a total of 216 trees. trees, how many of them are female employees?
某单位职工到郊外植树，其中(1/3)的职工各带一个孩子参加，男职工每人种13棵树，女职工每人种10棵，每个孩子种6棵，他们共种了216棵树，那么其中有女职工多少人．
<result>3</result>