Frame linking?!(編號:6286)

I have a problem about frames strucutes!
How do you write a code if you need a number from another frame?!
For exmaple: Frame1 Number of dogs : 4 and in frame2 I want number of cats to be double of dogs!
How do you plan a code?!
txtDog.text=2*txtCat.text ?!
Please help me