160.6×3/7+1/7×3/4+3/7×0.75 =
=160.6×3/7+0.25×3/7+0.75×3/7
=(160.6+0.25+0.75)×3/7
=161.6×3/7
=2424/35
=69又9/35
2006÷2007/2008
=2006÷2007×2008
=(2006×2008)÷2007
=(2007²-1)÷2007
=2007-1/2007
=2006又2006/2007