2 × 25 - 5 × [9 + 5 - 3 × (2x - 1)] = 25
50 - 5 × [14 - 3 × (2x - 1)] = 25
5 × [14 - 3 × (2x - 1)] = 50 - 25
5 × [14 - 3 × (2x - 1)] = 25
14 - 3 × (2x - 1) = 25 : 5
14 - 3 × (2x - 1) = 5
3 × (2x - 1) = 14 - 5
3 × (2x - 1) = 9
2x - 1 = 9 : 3
2x - 1 = 3
2x = 3 + 1
2x = 4
x = 4 : 2
x = 2