Can someone explain why collecting $980 cash on an account receivable would be +/- in the asset column? I don't think I have a good understanding of an account receivable. Why does it have to be specified that money was deducted from the account receivable?

from this post: https://www.chegg.com/homework-help/questions-and-answers/identify-following-separate-transactions-1-10-affects-financial-statements-increases-place-q34439532