How to validate one textbox is choosed another texbox read

Question

Hai Friends,


I ve the page like these


date = "textbox"
from = "textbox"
to = "textbox"
lodging = "textbox"
food bill = "textbox"
fixed claim = "textbox"


when the user tried to fill lodging+food bill +fixed allowance means ll show error "You caNT ALLOW ENTER FIXED ALLOWANCE"

condition is (lodging+food bills is filled means not allowed for fixed allowance,

they ch00sed fixed allowance means no (LOdging+food )