Đáp án đúng: B
Giải chi tiết:\(\begin{array}{l}\,\left( {\frac{7}{4} - \frac{3}{5}} \right) \times 20 = \left( {\frac{{35}}{{20}} - \frac{{12}}{{20}}} \right) \times 20\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,\,\,\,\,\frac{{23}}{{20}} \times 20\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,\,\,\,\,\,23\end{array}\)
Chọn B