Tính tổng: a) \[\frac{1}{8} + \frac{3}{8} + \frac{9}{8}\]; b) \[\frac{1} + \frac{3}{4} + \frac{6}{5}\]; c) \[\frac{3}{4} + \frac{1} + \frac{3}\]; d) \(\frac{2}{7} + \frac{3} + \frac{7}{5}\).