Find all solutions to $x(x+10) = 10(-10-x)$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Find all solutions to $x(x+10) = 10(-10-x)$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
x=-10
Find all solutions to $x(x+10) = 10(-10-x)$.
train