【1】(0.12-1又1/3+1又1/8)乘以(-3/4) =-0.12×3/4+4/3×3/4-9/8×3/4 =-0.09+1-1.5 =-0.59 【2】7/13乘以(-9)+7/13乘以(-18)+7/13 =7/13×(-9-18+1) =7/13×(-26) =-14 【3】29又23/24乘以(-12) =(30-1/24)×(-12) =-30×12+1/24×12 =-360+0.5 =-359.5