97*2008-96*2009
= （96+1）*2008-96*（2008+1）
=96*2008+2008-96*2008-96
=1912
0.91÷0.8+1.25×1.09
=0.91×1.25+1.25×1.09
=(0.91+1.09)×1.25
=2×1.25
=2.5