1. Problem: Identify which expressions have a sum of $\frac{7}{8}$.\n\n2. Calculate each sum:\n- $\frac{4}{8} + \frac{1}{8} + \frac{2}{8} = \frac{4+1+2}{8} = \frac{7}{8}$\n- $\frac{5}{8} + \frac{2}{8} = \frac{7}{8}$\n- $\frac{5}{4} + \frac{2}{4} = \frac{7}{4} \neq \frac{7}{8}$\n- $\frac{10}{8} - \frac{3}{8} = \frac{7}{8}$\n- $\frac{9}{8} - \frac{2}{8} = \frac{7}{8}$\n- $\frac{2}{3} + \frac{4}{3} + \frac{1}{2} = \frac{6}{3} + \frac{1}{2} = 2 + 0.5 = 2.5 \neq \frac{7}{8}$\n\n3. Expressions with sum $\frac{7}{8}$ are:\n- $\frac{4}{8} + \frac{1}{8} + \frac{2}{8}$\n- $\frac{5}{8} + \frac{2}{8}$\n- $\frac{10}{8} - \frac{3}{8}$\n- $\frac{9}{8} - \frac{2}{8}$