What are the methods to prove adequate finances for a single-entry tourist visa at the Royal Thai Embassy in Vientiane?

Hi mates, I have a question about the request of 60 days single entry tourist visa in Vientianne Royal Thai Embassy.

In the "Required documents list" on the site of embassy they write: "Evidence of adequate finance

• Single-Entry Tourist Visa: 20,000 baht per person".

My question is: how I can provide the proof of adequate finance? By cash or by other methods? Thanks in advance