\(a,250:\left(10-x\right)=25\\ \Rightarrow10-x=10\\ \Rightarrow x=0.\\b,3x-2018:2=23\\ \Rightarrow3x-1009=23\\ \Rightarrow3x=1032\\ \Rightarrow x=344. \)
a) \(250:\left(10-x\right)=25\)
\(10-x=250:25\)
\(10-x=10\)
\(x=10-10\)
\(x=0\)
b) \(3x-2018:2=23\)
\(3x-1009=23\)
\(3x=23+1009\)
\(3x=1032\)
\(x=1032:3\)
\(x=344\)