VTMO 2026 - Grade 6 - Semifinal - SET 3 - Self-study Question 2

Let $A=\frac12+\frac13+\frac14+\cdots+\frac1{2025}$ and $B=\frac1{2024}+\frac2{2023}+\frac3{2022}+\cdots+\frac{2023}{2}+\frac{2024}{1}$. Write $A/B=a/b$, where a and b are positive integers with greatest common divisor 1. Find a + b.