Juan borrowed a total of $13, which includes the $10 and the additional $3 from his mother. After selling $25 worth of lemonade, we can determine how much money he has.
- Amount earned from lemonade sales: $25
- Amount borrowed: $13
Now, we need to calculate how much money he has left after paying back his mother:
- Total money after sales: $25
- Amount owed to his mother: $3
Now, we subtract the amount he owes to his mother from the money he has:
\[ \text{Money left after paying back mother} = \text{Total money} - \text{Amount owed} \]
\[ \text{Money left} = 25 - 3 = 22 \]
Therefore, after paying back his mother, Juan will have $22 left.