The total amount Evan has is $1 + $12 = $<<1+12=13>>13.

So Evan still needs $20 - $13 = $<<20-13=7>>7.

# Answer

7
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
David found $12 on the street. He then gave it to his friend Evan who has $1 and needed to buy a watch worth $20. How much does Evan still need?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
7
David found $12 on the street. He then gave it to his friend Evan who has $1 and needed to buy a watch worth $20. How much does Evan still need?
train