A balky cow is leaving the barn as you try harder and harder to push her back

Question:

A balky cow is leaving the barn as you try harder and harder to push her back in. In coordinates with the origin at the barn door, the cow walks from x = 0 to x = 6.9 m as you apply a force with x-component F. = [20.0N + (3.0N/m} x]. How much work does the force you apply do on the cow during this displacement?