Jawabanmu

2014-06-10T17:21:21+07:00
Keliling = 2(p+l)
80 = 2 ( 6x-2+12)
80 = 2(6x+10)
40 = 6x + 10
30 = 6x
x = 5
panjang = 6x-2
x=5 ⇒ panjang = 6(5)-2 =28cm