(1-25%)x=72
0.75x=72
x=96
x-40%x=5.04
0.6x=5.04
x=8.4
x÷(1-40%)=3.6
x=3.6*60%
x=2.16
9分之4÷6+9分之5×6分之1
=4/9x1/6+5/9x1/6
=(4/9+5/9)x1/6
=1x1/6
=1/6
2-(4分之1+7分之1)×11分之4
=2-11/28x4/11
=2-1/7
=1又6/7
10-(39÷3分之13+13分之9)
=10-39x3/13-9/13
=10-9-9/13
=1-9/13
=4/13