A company distributes its product by train and by truck. The cost of distributing by train can be modeled as −0.07x^2 + 34x − 140, and the cost of distributing by truck can be modeled as −0.03x^2 + 29x − 150, where x is the number of tons of product distributed. Write a polynomial that represents the difference between the cost of distributing by train and the cost of distributing by truck.