请教一道英文的基础会计题,谢谢

请教一道英文的基础会计题,谢谢
题目是这样的：
Ricky decides to set up his own cricket coaching academy, he contribes 50000 of his personal savings into a business bank account under the name of PCS Ltd.书上是这样解释这个的： the impact of the initial transaction is that the business will have assets of 50000 in cash and also 50000 in own's equity, which represents 50000 owed to the owner. 为什么是现金增加50000呢?不是应该是银行存款增加50000吗?
接下来的一个业务是这样的：PCS Ltd sends invoice to Aussie for providing bowling ciaching services totalling 3000. Aussie will have 30's days credit.书上的解释是：Aussie will be recorded as a debtor(account receivable) and the services rendered will be shown as income.不是说收到钱后才能算作收入吗?AUSSIE不是有30天的付款期限吗,那现在还没收到钱怎么能算作收入呢?