what is the length of the rectangle ?

Answer:
[tex]\large\boxed{Length=4y^2\ meters}[/tex]
Step-by-step explanation:
The formula of an area of a rectangle:
[tex]A=wl[/tex]
w - width
l - length
We have
[tex]w=3y^3,\ A=12y^5[/tex]
Substitute:
[tex](3y^3)(l)=12y^5[/tex] divide both sides by 3y³
[tex]l=\dfrac{12y^5}{3y^3}[/tex] use [tex]\dfrac{a^n}{a^m}=a^{n-m}[/tex]
[tex]l=4y^{5-3}\\\\l=4y^2[/tex]