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? Let's think step by step and output the final answer after "####".
user
The total amount Evan has is $1 + $12 = $<<1+12=13>>13.
So Evan still needs $20 - $13 = $<<20-13=7>>7.
#### 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