Multi-turn user requests:
user: In attempting to log into my travel account using both my established client id 'client_520', secret 'rise_to_sky' and refresh token 'token990125', I seem to be at a bit of an impasse. Assistance with the authentication process would be immensely appreciated.
user: I've recently linked a newly registered credit card with the ID 'card_4455', set to expire in 2024, and it's under my name. Accessing my account to ascertain my current balance is my next goal. Could this information be retrieved using access token 'abc123xyz456' for me?
user: Having reviewed my financial standing, I now need to compute the average amount spent in my last quintet of purchases. Guidance in deriving this mean value would be beneficial.
user: The amounts are 45.99, 78.25, 102.50, 38.75, and 92.10.

Ground-truth function call sequence:
TravelAPI.authenticate
TravelAPI.register_credit_card
TravelAPI.get_credit_card_balance
MathAPI.mean