9
Step-by-step explanation:
Hey there mate ;)
As per question,
Debby borrowed $10, $4 and paid back $5
[tex]→10 + 4 - 5[/tex]
[tex]→14 - 5[/tex]
[tex]→9[/tex]
So, the answer is 9
The amount of money Debby owes her sister is $9.
When Debby borrows money, the amount of her debt increases and when she pays back her debt decreases. So, when she borrows, the amount she borrows is added and when she pays back, the amount is subtracted.
$10 - $5 + 4 = $9
To learn more about addition, please check: https://brainly.com/question/19628082