You have a cube with side 2 rst units.
In order to calculate the volume of the given cube, you use the following formula:
V = a³
where a is the length of cube sides.
By replacing the value of a into V formula you obtain:
V = (2 srt)³ units³
V = 8 r³s³t³
where you have used tha fact 2³=8 and that variables r,s and t power to 3 are equal to r³s³t³.
Hence, the volume of the given cube is V = 8 r³s³t³ units³