David's revenue for the 50 kilograms of rice is $1.20 x 50 = $<<1.20*50=60>>60.

So, his profit is $60 - $50 = $<<60-50=10>>10.

# Answer

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<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A sack of rice, which is 50 kilograms,  costs $50. If David sells it for $1.20 per kilogram, how much will be his profit?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
10
A sack of rice, which is 50 kilograms,  costs $50. If David sells it for $1.20 per kilogram, how much will be his profit?
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