Tính hợp lý

B

- Hướng dẫn giải

Đáp án B

$$\begin{gathered} A=\left(4\frac{5}{17}-3\frac{4}{5}+8\frac{15}{29}\right)-\left(3\frac{5}{17}-6\frac{14}{29}\right) \\ A=4\frac{5}{17}-3\frac{4}{5}+8\frac{15}{29}-3\frac{5}{17}+6\frac{14}{29} \\ A=\left(4\frac{5}{17}-3\frac{5}{17}\right)+\left(8\frac{15}{29}+6\frac{14}{29}\right)-3\frac{4}{5} \\ A=\left(4-3\right)+\left(\frac{5}{17}-\frac{5}{17}\right)+\left(8+6\right)+\left(\frac{15}{29}+\frac{14}{29}\right)-3\frac{4}{5} \\ A= 1+0+14+1-3\frac{4}{5} \\ A= 16-3\frac{4}{5} \\ A= 15\frac{5}{5}-3\frac{4}{5}=12\frac{1}{5} \end{gathered}$$