(3×x-8)[(203×4-207)÷5+240×3-(767-312÷12)]=100
(3×X-8)[(812-207):5 +720 - (767 - 26)]=100
(3×X-8)(605 : 5 +720-741) = 100
(3×X-8) (121 + 720 - 741) = 100
(3×X-8)(841 - 741) = 100
(3×X- 8) × 100 = 100
3×X - 8 = 100 : 100
3×X - 8 = 1
3×X = 1 + 8
3×X = 9
X = 9 : 3
X = 3