## Answer :

1.

**Calculate the width of the rectangle:**

- The area of a rectangle is given by the formula:

[tex]\[ \text{Area} = \text{Length} \times \text{Width} \][/tex]

- Here, the area is 135 square units and the length is 9 units.

- Therefore, we can determine the width by rearranging the formula to solve for width:

[tex]\[ \text{Width} = \frac{\text{Area}}{\text{Length}} = \frac{135}{9} = 15 \text{ units} \][/tex]

2.

**Apply the Pythagorean theorem:**

- To find the diagonal of the rectangle, we treat the length, width, and diagonal as sides of a right triangle. The formula from the Pythagorean theorem is:

[tex]\[ c = \sqrt{a^2 + b^2} \][/tex]

where [tex]\(c\)[/tex] is the hypotenuse (diagonal), and [tex]\(a\)[/tex] and [tex]\(b\)[/tex] are the legs (length and width of the rectangle).

- Here, [tex]\(a = 9\)[/tex] units (length) and [tex]\(b = 15\)[/tex] units (width).

3.

**Calculate the diagonal:**

- Plugging in the values:

[tex]\[ c = \sqrt{9^2 + 15^2} = \sqrt{81 + 225} = \sqrt{306} \][/tex]

- Now, compute the square root of 306:

[tex]\[ \sqrt{306} \approx 17.4928556845359 \][/tex]

4.

**Round the result to the nearest tenth:**

- Rounding 17.4928556845359 to the nearest tenth:

[tex]\[ 17.5 \text{ units} \][/tex]

Therefore, the length of the diagonal of the rectangle is approximately [tex]\(17.5\)[/tex] units.