If you have $30 and spend $40, you are short by $10. To cover the extra $10, you would need to:
1. **Use a Credit Card**: Charge the additional $10 to your credit card.
2. **Borrow Money**: Obtain the extra $10 from someone else.
3. **Use Savings**: Dip into savings or another account to cover the shortfall.
Without one of these options, you wouldn't have been able to complete the purchase with just the $30.
