PIMSO 2021 - Mathematics - Grade 6 - National Round Question 6

Find the sum of $\dfrac{3}{6\times9}+\dfrac{3}{9\times12}+\dfrac{3}{12\times15}+\dfrac{3}{15\times18}+\dfrac{3}{18\times21}+\cdots+\dfrac{3}{96\times99}+\dfrac{3}{99\times102}$.