panjang:lebar = 7:5 keliling =120M.luasnya adalah.....M2

K = 2p + 2l
= 2(7x) + 2(5x)
= 14x + 10x
= 24x

120 = 24x
x = 120 / 24
x = 5

P = 7(5) = 35 m
L = 5(5) = 25 m

luas = 35 x 25
 875 m2

Keliling = 2P + 2L
120 = (2 x 7y) + (2 x 5y)
120 = 14y + 10y
120 = 24y
y = 5

P = 7 x 5 = 35
L = 5 x 5 = 25
Luas = P x L
         = 35 x 25 = 875
Jadi luasnya 875 m2