Вычислить: а) 2/5 − 3/5; б) (2/5 + 3/5) − (2/5 − 3/5).

а) \(\frac{2}{5}-\frac{3}{5}=\frac{2-3}{5}=-\frac{1}{5}\).

б) \(\left(\frac{2}{5}+\frac{3}{5}\right)-\left(\frac{2}{5}-\frac{3}{5}\right)=1-\left(-\frac{1}{5}\right)=\frac{6}{5}=1\frac{1}{5}\).

Ответ: а) \(-\frac{1}{5}\); б) \(\frac{6}{5}\).