Chapter A, Problem 24E

To determine

The missing term of the expression $\frac{3}{7}{\left(t+1\right)}^{\frac{7}{3}}-\frac{3}{4}{\left(t+1\right)}^{\frac{4}{3}}=\frac{3{\left(t+1\right)}^{\frac{4}{3}}}{28}\left(\boxed{}\right)$ in the box.