2×{3×3×11:[2×2+(3-a)×2+1]}-18=0
2×{3×3×11:[2×2+(3-a)×2+1]} = 18
3×3×11:[2×2+(3-a)×2+1] = 18 : 2
99 : [ 4 + (3 - a ) × 2 + 1] = 9
4 + (3 - a ) × 2 + 1 = 99 : 9
4 + (3 - a ) × 2 + 1 = 11
(3 - a ) × 2 = 11 - 4 - 1
(3 - a) × 2 = 6
3 - a = 6 : 2
3 - a = 3
a = 3 - 3
a = 0
