(1)4.05÷0.5+10.75
=8.1+10.75
=18.85
(2)21.6÷0.8-1.2×5
=27-6
=21
(3)6.8×2.7+2.7×3.2
=(6.8+3.2)×2.7
=10×2.7
=27
(4)8.4×6.9÷(6.44-4.14)
=8.4×6.9÷2.3
=8.4×(6.9÷2.3)
=8.4×3
=25.2
(5)0.38×102
=0.38×(100+2)
=0.38×100+0.38×2
=38+0.76
=38.76
(6)4.8÷2.5÷4
=4.8÷(2.5×4)
=4.8÷10
=0.48