Jawabanmu

2014-01-14T15:15:49+07:00
Perbandingan panjang dan lebar = 7:5
panjang = 7x
lebar = 5x
Keliling = 1440m
2(p+l) = 1440 m
2(7x+5x)= 1440
2.12 x = 1440
24x= 1440
x=60

panjang = 7x = 7.60 = 420
lebar  = 5x = 5.60 = 300

Luas = p x l = 420 x 300 = 126000  m^{2}
2 2 2