Let the length, width and height be 3cm, 2kcm and kcm respectively.

3k= 18

k=6

Width 12cm, height 6cm.

2.

4(3k+2k+k)=96

k=4

Length 12cm, width 8cm and height 4cm.

3.

The speed of the satellite is 40/57 of that of the spacecraft.

The speed of the spaceship is 57/40 of that of the satellite.

The speed of the spacecraft is11.4km per second.