Jawabanmu

2014-05-29T13:31:59+07:00
L=a.t
     2
105=30.(2x-3)
           2
210=60x-90
60x=210+90
60x=300
  x=300
       60
   x=5 cm
2014-05-29T13:35:16+07:00
L = 1/2 × alas × tinggi 30 cm = 1/2 × 30 cm × (2x-3) 30 cm = 15 cm (2x-3) 30 cm = 30x cm -45 cm 75 cm = 30x cm X = 75/30 = 2 1/2 Tinggi = 2 cm
Eh, maaf salah..
Sebentar...saya perbaiki dulu...
L=a.t
2
105=30.(2x-3)
2
210=60x-90
60x=210+90
60x=300
x=300
60
x=5 cm
Tinggi nya = 7 cm