200 : x + 400 : x = 2
(200 + 400) : x = 2
600 : x = 2
x = 600 : 2
x = 300
200 : x + 400 : x = 2
200 + 400 = 2x
600 = 2x
2x = 600
x = 600 : 2
x = 300
\(x:200:x+400:x=2\)
\(\left(200+400\right):x=2\)
\(600:x=2\)
\(x=600:2\)
\(x=300\)
200 : x + 400 : x = 2
(200 + 400) : x = 2
600 : x = 2
x = 600 : 2
x = 300