in cash or by cash

[putr1s]

dear all English teacher

I am confused in using a sentence with proposition especially:
1, why my teacher told me to use a word I pay in cash , why not cashI pay by cash ???
2. and then instead of pay in credit card, why i have to use pay by credit card ???
please help me, thank you

[Casiopea]

Cash payment is direct, so in cash, not by cash. Mind you, some people I know would say 'by cash'.

All the best.

Check out this source: HLT Magazine (May 2001) - Seth Lindstromberg column

"...if you pay by check, the check is a means by which you pay. But, it is not payment in itself! Not yet. The person you give the check to receives payment only when the check is cashed. So the check is between the beginning and the end of the transaction.
A cash payment is different. The cash is the payment; there is nothing in between. (The same is true of so-called 'payment in kind'--which is when, for example, to buy 20 potatoes, you pay with 1 chicken.)

The term, payment in cash, then, means 'payment in the form of cash'. The cash is the end of the transaction. If you ask: "Where is the payment, where is the end of the transaction?" The answer is: "Look. It is here. In this cash."

[Casiopea]

Welcome. putr1s.

[putr1s]

Hi, Casiopea
Thank you for your explanation and help. Now, I can understand how to put in and by for cash. I wish we will be friends and I wish you would help me to improve my English.
Once again, Thank you very much. Nice to know you

[Casiopea]

You're most welcome and I hope to see you soon.