35 bones at the end - 10 received = <<35-10=25>>25 on Sunday.

Lassie ate half, so multiply by two to find the number of bones at the beginning which is 25 * 2 = <<25*2=50>>50 bones.

# Answer

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<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Lassie eats half of her bones on Saturday. On Sunday she received 10 more bones. She now has a total of 35 bones. How many bones did she start with before eating them on Saturday?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
50
Lassie eats half of her bones on Saturday. On Sunday she received 10 more bones. She now has a total of 35 bones. How many bones did she start with before eating them on Saturday?
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