`3/5:(-1/15-1/6)+3/5:(-1/3-1 1/15)`
`=3/5:[-7]/30+3/5:[-7]/5`
`=3/5 . [-30]/7+3/5 . [-5]/7`
`=3/5 .([-30]/7+[-5]/7)`
`=3/5 . [-5]=-3`
\(\dfrac{3}{5}:\left(-\dfrac{1}{15}-\dfrac{1}{6}\right)+\dfrac{3}{5}:\left(-\dfrac{1}{3}-1\dfrac{1}{15}\right)\)
\(=\dfrac{3}{5}:\left(-\dfrac{6}{90}-\dfrac{15}{90}\right)+\dfrac{3}{5}:\left(-\dfrac{1}{3}-\dfrac{16}{15}\right)\)
\(=\dfrac{3}{5}:\dfrac{-7}{30}+\dfrac{3}{5}:\left(-\dfrac{5}{15}-\dfrac{16}{15}\right)\)
\(=\dfrac{3}{5}:\dfrac{-7}{30}+\dfrac{3}{5}:\dfrac{-7}{5}\)
\(=\dfrac{3}{5}\times\dfrac{-30}{7}+\dfrac{3}{5}\times\dfrac{-5}{7}\)
\(=\dfrac{3}{5}\times\left(\dfrac{-30}{7}+\dfrac{-5}{7}\right)\)
\(=\dfrac{3}{5}\times\left(-5\right)\)
\(=-3\)
