6. The area of a rectangular field is given by the trinomial t2 - 4t - 45. The length of the rectangle is t + 5. What is the expression for the width of the field?

The area of a rectangle is simply the product of its length times its width. To get the width, the area is divided by its length. Dividing the trinomial t2-4t-45 by (t+5) results to (t - 9) which is the expression for the width of the field.