`150:(40:x-2)=3`
`40:x-2=150:3=50`
`40:x=50+2`
`40:x=52`
`x=40:52`
`x=10/13`
\(40:x-2=150:3\\ 40:x-2=50\\ 40:x=52\\ x=\dfrac{10}{13}\)
`150 : ( 40 : x - 2) = 3`
`=> 40 : x - 2 = 150 : 3`
`=> 40 : x - 2 = 50`
`=> 40 : x = 50 + 2`
`=> 40 :x = 52`
`=> x = 40/52 = 10/13`