Answer
$ \frac{28}{21} \cdot 640 \cdot \frac{15}{32} = 400$
Work Step by Step
$ \frac{28}{21} \cdot 640 \cdot \frac{15}{32} = \frac{28}{21} \cdot \frac{640}{1} \cdot \frac{15}{32} = \frac{28}{21} \cdot \frac{20}{1} \cdot \frac{15}{1} = \frac{4}{3} \cdot \frac{20}{1} \cdot \frac{15}{1} = \frac{4}{1} \cdot \frac{20}{1} \cdot \frac{5}{1} = \frac{4 \cdot 20 \cdot 5}{1} = \frac{400}{1} = 400$
