Answer:
see explanation
Step-by-step explanation:
1
The area of a rectangle = length × width
2
To find the width, divide the area by the length
3
width = [tex]\frac{area}{length}[/tex] = [tex]\frac{3x^2+9x}{3x}[/tex]
To simplify divide each term on the numerator by 3x
= [tex]\frac{3x^2}{3x}[/tex] + [tex]\frac{9x}{3x}[/tex] = x + 3 ← width
