The question as you have typed it makes no sense at all! I assume that “Bad debt: RM1900” means that there is already an expense of 1900 for the year and now they are writing off an additional irrecoverable debt?
If so, then increase the expense by 620 (for the SOPL) and reduce receivables by 620 (in the SOFP).
Have you watched my free lectures on irrecoverable and doubtful debts? The lectures are a complete free course for Paper F3 and cover everything needed to be able to pass the exam well. You cannot expect me to type out all my lectures here 🙂