Sean says that to add a number to –100 and still have –100 is to add zero. candice says that she can add two numbers to –100 and still have –100. who is correct and why?

Sean : -100 + 0 = -100...this is correct...this is the identity property
candice : - 100 + 100 + (-100) = -100...this is correctif ur allowed to add negative numbersor -100 + 0 + 0 = -100and if u can add 2 zero's

Need the graph to answer this.