How does marijuana interact with tranxene (clorazepate)?

Not directly: Tranxene (clorazepate) is a benzodiazepine and works on GABA receptors. Marijuana has its own receptors, so there is no direct interaction. However, both are sedating, can affect cognition, alertness, etc. It's not a safe combination.

Lack of cordination : When they are used together, the risk of excessive sedation and other side effects may be increased. Oversedation including daytime drowsiness, confusion, disorientation, and uncoordinated movement can occur. Slowed reaction time may make trying to drive hazardous. Low body temperature and the inability to walk are serious side effects that need a doctor's attention.

The combination can: Cause coma, peripheral edema, spontaneous abortion, hepatic encephalopathy and trouble with thinking. Not a good combination!