[tex]\dfrac{9}{10}=\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{15}[/tex]
[tex]\dfrac{1}{2}=\dfrac{15}{30}\\\\\dfrac{1}{3}=\dfrac{10}{30}\\\\\dfrac{1}{15}=\dfrac{2}{30}\\\\\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{15}=\dfrac{15}{30}+\dfrac{10}{30}+\dfrac{2}{30}=\dfrac{15+10+2}{30}=\dfrac{27}{30}=\dfrac{9}{10}[/tex]
