GridView with CheckBox and TextBox Validation

Question

I have a gridview with checkbox and textbox. Id like to put in validation that would check for either checkbox = checked and textbox left empty and/or checkbox not checked and textbox has values.

 

How can i do it?

 

This is layout:

 

This validation would happen when i press submit. I cant figure out how to do it and i have no knowlege of javascript.

 

Please help.

THank You