5.4-1.5×2.6
=3×1.8-3×1.3
=3×（1.8-1.3）
=3×0.5
=1.5
3/5÷[(3/4-2/3)×4]
=3/5÷[1/12×4]
=3/5÷1/3
=3/5×3
=1.8
30.8÷[14-(9.85+1.07 ）]
=30.8÷[14-10.92]
=30.8÷3.08
=10