C35 Trigonometry

"What windfall? I'm borrowing this from someone else. It's just that I don't want to owe you money. Cut the crap, continue teaching me." I glared at her unhappily.

"Hoho, if you don't want to say it, then forget it. Seeing that I'm still your sister, I'll continue teaching you. After all, you even gave me 200 yuan."

Wang Xinmei laughed happily.

"Elder sister? You can support yourself