Answer: They are liable for punishment for their act.
Step-by-step explanation:
The legal punishment for crime under the influence of intoxication, does not get any defense in the case of general intent of offence.
According to the given situation, Rex and Anah had planned the robbery and otherwise no robbery can be conducted under the severe drug intoxication. So, here mensrea and actus reus both are involved. The mensrea because they had plan the robbery and actus reus is what they plan and performed. So, they are liable to get the punishment.