Jawabanmu

2014-04-07T11:53:52+07:00
2014-04-07T11:58:14+07:00
90 km/jam : 5/18 = 25 m/s
20 menit = 20 × 60 = 1200 sekon
25 × 1200 = 30.000 m
30.000 m/20 s atau 5400 km/jam