424-2x[872-1000:(5+1xX)]:4=8
2x[872-1000:(5+X)]:4 = 424-8
2x[872-1000:(5+X)]:4 = 416
[872-1000:(5+X)]:4 = 416:2
[872-1000:(5+X)]:4 = 208
872-1000:(5+X) = 208×4
872-1000:(5+X) = 832
1000:(5+X) = 872-832
1 000:(5+X) = 40
5+X = 1 000:40
5+X = 25
X = 25-5
X = 20
