a) $\frac{5}{3}-\frac{7}{3}=$

Step 1 ：Given the problem: \(\frac{5}{3}-\frac{7}{3}\)

Step 2 ：Since the denominators are the same, we can subtract the numerators: \(\frac{5-7}{3}\)

Step 3 ：Simplify the numerator: \(\frac{-2}{3}\)

Step 4 ：\(\boxed{-\frac{2}{3}}\) is the final answer.