Jawabanmu

2014-09-11T21:34:06+07:00
120 x 2 = 240
240 : 8 = 30
30 - 18 = 12 cm
jadi jawabnnya 12 cm
34 4 34
2014-09-11T21:38:49+07:00
L = ( p + l ) x t x 1/2
120 = ( p + 18 ) x 8 x 1/2
120 = ( p + 18 ) x 4
120 = 4p + 72
-4p = 72 - 120
-4p = -48
p = -48 : -4
p = 12