Concatenating the tuple $(40,50)$ to tuple$1$ from Part $($b$),$ as in

tuple$1+=(40,50)$

creates a new tuple, then assigns a reference to it to the variable tuple$1$tuple$2$ still refers to the original tuple.

In the following snippets, after the two assignments, tuple$1$ and tuple$2$ are two different copies of the same tuple object:

In $[1]$: tuple$1=(10,20,30)$

In $[2]$: tuple$2=$ tuple$1$

In $[3]$: tuple$2$

Out$[3]$: $(10,20,30)$

The $+=$ augmented assignment statement can be used with strings and tuples, even though they're immutable.

For a string or tuple, the item to the right of $+=$ must be a string or tuple, respectively$$mixing types causes a TypeError.