(1)(12 1 12 - 5 6 ×3)÷3 1 3 =(12 1 12 - 5 2 )÷ 10 3 = 115 12 × 3 10 = 23 8 答:商是 23 8 .(2) 1 2 ÷( 87 78 × 78 87 - 1 6 )= 1 2 ÷(1- 1 6 )= 1 2 ÷ 5 6 = 1 2 × 6 5 = 3 5 答:商是 3 5 .