Đáp án đúng: D
Giải chi tiết:\(\begin{array}{l}\,\frac{3}{5} \times \frac{7}{8} + \frac{1}{2} \times \frac{7}{5} = \frac{{21}}{{40}} + \frac{7}{{10}}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{21}}{{40}} + \frac{{28}}{{40}}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{49}}{{40}}\end{array}\)
Chọn D