大致有如下可能:
8 × (9 ÷ (10 - 7))
8 × 9 ÷(10 - 7)
(8 × 9) ÷ (10 - 7)
(8 ÷ (10 - 7)) × 9
8 ÷ (10 - 7) × 9
8 ÷ ((10 - 7) ÷ 9)
(9 × 8) ÷ (10 - 7)
(9 ÷ (10 - 7)) × 8
9 ÷ (10 - 7) × 8
9 ÷ ((10 - 7) ÷ 8)
9 × (8 ÷ (10 - 7))
9 × 8 ÷(10 - 7)