Find the center of the ellipse whose equation is $9x^2 + 72x + 4y^2 - 8y - 176 = 0.$
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Find the center of the ellipse whose equation is $9x^2 + 72x + 4y^2 - 8y - 176 = 0.$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
(-4,1)
Find the center of the ellipse whose equation is $9x^2 + 72x + 4y^2 - 8y - 176 = 0.$
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