có 2 cau là b và c

Bài giải a) $\frac{21}{47}+\frac15+\frac{26}{47}$ Ta có: $\frac{21}{47}+\frac{26}{47}+\frac15$ $= \frac{21+26}{47}+\frac15$ $= \frac{47}{47}+\frac15$ $= 1 + \frac15$ $= \frac{5}{5} + \frac15$ $= \frac{6}{5}$ b) $\frac38.\frac53-\frac38.\frac23$ Ta có: $\frac38.\frac53-\frac38.\frac23$ $= \frac38.(\frac53-\frac23)$ $= \frac38.(\frac{5-2}{3})$ $= \frac38.\frac33$ $= \frac38.1$ $= \frac38$