Followup on authority

Sir you said why would Sam need implied authority for borrowing money when he has express authority for borrowing money. But Sir how you are saying that he has express authority for borrowing money because its not mentioned anywhere in question.
Here was the question

Ham, Sam and Tam formed a partnership to run a petrol station. The partnership agreement expressly stated that the partnership business was to be limited exclusively to the sale of petrol.
In January 20X8 Sam received £10,000 from the partnership’s bank drawn on its overdraft facility. He told the bank that the money was to finance a short-term partnership debt but in fact he used the money to pay
for a round-the-world cruise. In February 20X8 Tam entered into a £15,000 contract on behalf of the partnership to buy a stock of bicycles, which he hoped to sell from the garage forecourt.