4/9÷(5/6-0.2)
=4/9÷(5/6-1/5)
=4/9÷(25/30-6/30)
=4/9÷19/30
=120/171
10.5×(3.8-0.8)÷6.3
=10.5×3÷6.3
=10.5÷2.1
=5