Question

Can anyone help with this? (Ignore question b)

Answer 1

The rate of the flow is the current. The junction is just like a junction in a parallel circuit.  Therefore the rate of flow will be the same in x, y and z

Answer 2

-- ' Y ' plus ' Z ' must be equal to ' X ' .


-- A more elegant statement:   

           (The sum of everything flowing into the junction)
is equal to
           (the sum of everything flowing out of the junction).


-- An even more elegant statement:

If water flowing into the junction is positive and
water flowing out of the junction is negative, then

     (The sum of all flow at the junction)  =  Zero.


The reason for all of these statements is the Law of Conservation of Water:

                   Water can't be created or destroyed.

If there are no faucets or leaks at the junction, then the flow in and
the flow out are equal.