3/5:x=3/20-2/5
3/5:x=-1/4
x=3/5:-1/4
x=-12/5
`2 / 5 + 3 / 5 : x = 3 / 20`
`3 / 5 : x = 3 / 20 - 2 / 5`
`3 / 5 : x = [-1] / 4`
`x = 3 / 5 : [-1] / 4`
`x = [-12] / 5`
\(\dfrac{2}{5}+\dfrac{3}{5}:x=\dfrac{3}{20}\\ \dfrac{3}{5}:x=\dfrac{3}{20}-\dfrac{2}{5}\\ \dfrac{3}{5}:x=\dfrac{-1}{4}\\ x=\dfrac{3}{5}:\left(\dfrac{-1}{4}\right)\\ x=\dfrac{3}{5}.\left(\dfrac{-4}{1}\right)\\ x=\dfrac{-12}{5}\)