\(\dfrac{3\times145+3\times55}{6\times215+6\times85}=\dfrac{3\times\left(145+55\right)}{6\times\left(215+85\right)}=\dfrac{3\times200}{6\times300}\)\(=\dfrac{3\times100\times2}{3\times2\times100\times3}=\dfrac{2}{2\times3}=\dfrac{2}{6}=\dfrac{1}{3}\)
