0.91÷4/5+1.25×1.09
=0.91×5/4+5/4×1.09
=(0.91+1.09)×5/4
=2×5/4
=5/2
48×（5/6+5/8-5/12-7/16）
=48×5/6+48×5/8-48×5/12-48×7/16
=40+30-20-21
=29