\frac{8}{21}
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Multiply $\frac{2}{3}$ by $\frac{4}{7}$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
\frac{8}{21}
Multiply $\frac{2}{3}$ by $\frac{4}{7}$.
train