P=480 m
L=135 m
---------/----------
Aria=? m² , ari.
-------//-----------
P=2*(L+l)
P=2L+2l
2l=P-2L
[tex]\boxed{l= \frac{P-2L}{2}} [/tex]
[tex]l= \frac{480-2*135}{2} = \frac{480-270}{2}= \frac{210}{2}=105 ~m [/tex]
Aria=L*l
Aria=135*105
Aria=14175 m²
Aria=141,75 ari.