Generally written

Eight years ago, a classmate fell seriously ill, and the costs were said to be around three to four hundred thousand. Donations were initiated in the class group, and everyone contributed to varying degrees. I also donated 1,000 yuan.
When we were in school, our relationship was fairly good. During his hospitalization, a few of us went to visit him once. During our conversation, he said that the funds he raised were still not enough for the upcoming treatment costs. I asked him how much more he needed. He said he needed around 50,000 more.
We helped him raise the 50,000 and transferred it to him. He insisted on writing us an IOU, saying that once he recovered, he would definitely pay us back.