we are supposed to explain
Which situation could be solved using the equation

As we can see in the given equation , one number is -4 and the other number is 4
When we add two number of same value but opposite in sign we get zero.
This equivalent to the real life situation of paying a post paid bills.
Suppose you are using a post paid service , and the bills gets generated at the end of the month.
Suppose the bills amount is $x.
Once you pay that bills , then total outstanding again becomes $0.
Because
