Answer: 12
Explanation: In FCC metal lattice there are total four octahedral slip plane and six direction where each are common to two octahedral plane and so that gives total of three slip direction . So the total slip system is multiplication of the slip plane and the slip direction that is twelve.
Slip system=Slip plane×Slip direction
Slip system =4×3=12
Therefore there are total 12 slip system in the FCC metal lattice.