Need help with a formula.

Hello,

  I am trying to do something with a pre-existing formula but haven't been able to get it working.  Right now I have the formula...

var DV = this.getField("15 Depreciated Value");

var age = this.getField("Age");

var AC = this.getField("14 Acquisition Cost");

var DR = AC.value/60;

1. DV.value = 0;
2. DV.value = AC.value - (DR*age.value);

if(DV.value<0) DV.value=0;

if(DV.value>=500) DV.textColor =color.red;

if (DV.value<500) DV.textColor=color.black;

But it doesn't do everything I need.  Right now it calculates depreciated value every month, but I need it to do it differently.  I tried adding the below code...

if (Age.value<=12) DV.value=AC.value*0.7

if (Age.value>=24) DV.value=AC.value*0.4

if (Age.value>=36) DV.value=AC.value*0.2

if (Age.value>=48) DV.value=AC.value*0.1

if (Age.value>=60) DV.value=AC.value*0.05

To adjust the Depreciated Value better but it doesn't seem to work.

I'm trying to do something like...

Depreciated Value = Acquisition Cost * 0.7 if Age is 01-12

Depreciated Value = Acquisition Cost * 0.4 if Age is 13-24

Depreciated Value = Acquisition Cost * 0.2 if Age is 25-36

Depreciated Value = Acquisition Cost * 0.1 if Age is 37-48

Depreciated Value = Acquisition Cost * 0.05 if Age is greater than 49

Any help would be greatly appreciated! Thank you for your time and assisatnace!