几道简算题，急啊~~

18x(-9又1/108)
=-(18x9又1/108)
=-162又1/6

（-1/3-1/5+1/7)x(-105)
=-41/105x(-105)
=-41

-7x(+79又13/14)
=-(7x79又13/14）
=-559又1/2

（-24/13)x[-13/8-(1/7)x(-13/12)]
=-24/13x-499/336
=-499/182

回答者： 楚冷寒 - 魔法学徒 一级 2009-9-21 21:58

检举1)
18x(-9又1/108)
=-18*(9*108+1)/108
=-18*973/108
=-973/6
=-162又1/6
2)
（-1/3-1/5+1/7)x(-105)
=[(-5×7)/(3×5×7)-(3×7)/(3×5×7)+(3×5)/(3×5×7)] ×(-105)
=[(-35-21+15)/105]×(-105)
=(-41)/(-1)
=41
3)
-7x(+79又13/14)
=-7×(79×14+13)/14
=-1119/2
= -559又1/2
4)
（-24/13)x[-13/8-(1/7)x(-13/12)]
=（-24/13)x[-13/8+13/(7×12)]
=-(24/13)[(13×2)/(7×3×4×2)-(13×3×7)/(7×3×4×2)]
=-(24/13)( 13×2-13×3×7)/ (7×3×4×2)
=-24(2-21)/168
=24×19/168
=19/7
=2又5/7

4)另一种解法
（-24/13)x[-13/8-(1/7)x(-13/12)]
=24x[1/8-1/(7×12)]
=6x(1/2-1/21)
=6x(21-2)/42
=