40:x+18-(-2)=10
40:x+20 =10
40:x =10-20
40:x =-10
x =40:(-10)
x =-4
\(40:x+18-\left(-2\right)=10\\ \Leftrightarrow\dfrac{40}{x}+20=10\\ \Leftrightarrow\dfrac{40}{x}=-10\\ \Leftrightarrow x=40:\left(-10\right)=-4\)
40 : x + 18 - (-2) = 10
40 : x + 18 + 2 = 10
40 : x + 18 = 10 - 2
40 : x + 18 = 8
40 : x = 8 - 18
40 : x = -10
x = 40 : (-10)
x = -4