If $2x = 5y$ and $7y = 10z$, what is the value of $\frac{z}{x}$ expressed as a common fraction?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
If $2x = 5y$ and $7y = 10z$, what is the value of $\frac{z}{x}$ expressed as a common fraction?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
\frac{7}{25}
If $2x = 5y$ and $7y = 10z$, what is the value of $\frac{z}{x}$ expressed as a common fraction?
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