Answer:
288cm²
Explanation:
The volume of a rectangular prism can be easily calculated by multiplying the height by the width by the length 
Assuming that the lengths given ( 6cm, 4cm and 12cm ) are the width, height and length 
If so then the volume is equal to 6 * 4 * 12 
6 * 4 = 24 
24 * 12 = 288
volume = 288cm²