4除以5分支4减5分支4除以4
=4÷4/5-4/5÷4
=5-1/5
=24/5
3分支2-(6分支5-4分支3)除以8分支3
=2/3-(10/12-9/12)÷3/8
=2/3-1/12×8/3
=2/3-2/9
=6/9-2/9
=4/9