tolong dong..besok ujian ni...pliiiisss...

Keliling persegi panjang : 2(p+l)
2(60+80)
= 2 (140)
=280 m

Jarak antar lampu : 4 m
280 : 4 = 70

Harga 1 lampu = Rp 30.000
70 x 30.000 = C. Rp 2.100.000

^_^