1. Let's verify each fraction operation step-by-step. 2. For the first line: $\frac{3}{4} \times \frac{5}{6} = \frac{15}{24} = \frac{5}{8}$ (simplified). 3. For the second line: $\frac{1}{8}$ is just a fraction, no operation. 4. For the third line: $1 \frac{2}{16} = 1 + \frac{2}{16} = 1 + \frac{1}{8} = \frac{8}{8} + \frac{1}{8} = \frac{9}{8}$. 5. For the fourth line: $\frac{12}{16} + \frac{15}{16} + \frac{2}{16} + \frac{27}{16} + \frac{27}{16} - \frac{2}{16} = \frac{12+15+2+27+27-2}{16} = \frac{81}{16}$. The user wrote $\frac{25}{16}$ which is incorrect. 6. For the fifth line: $\frac{4}{5}$ and $\frac{2}{5} \quad \frac{1}{4}$ are fractions, no operation shown. 7. For the sixth line: $\frac{8}{20} + \frac{5}{20} = \frac{13}{20}$ correct. 8. For the seventh line: $\frac{6}{20} - \frac{5}{20} = \frac{1}{20}$ correct. 9. For the eighth line: $20 - 13 = 7$ correct. 10. For the ninth line: $\frac{7}{20}$ is just a fraction, no operation. 11. For the tenth line: $\frac{5}{6}$, $\frac{1}{12}$, $\frac{1}{10}$ are fractions, no operation shown. 12. For the eleventh line: $\frac{49}{60}$ is a fraction, no operation. 13. For the twelfth line: $\frac{50}{60} + \frac{5}{60} = \frac{55}{60}$ correct. 14. For the thirteenth line: $\frac{55}{60} - \frac{6}{60} = \frac{49}{60}$ correct. Summary: All fraction operations are correct except the sum in step 5 where the user wrote $\frac{25}{16}$ but the correct sum is $\frac{81}{16}$. Final answer: The only mistake is in the sum $\frac{12}{16} + \frac{15}{16} + \frac{2}{16} + \frac{27}{16} + \frac{27}{16} - \frac{2}{16} = \frac{81}{16}$, not $\frac{25}{16}$.