consider arithmetic modulo 14. Determine which of the following functions are bijective.If it is bijective determine the inverse function.

i.) $\displaystyle f: \mathbb{Z}_{14} \rightarrow \mathbb{Z}_{14}:

f([a]_{14})=[a]_{14}\cdot[3]_{14}; $

ii.)$\displaystyle f: \mathbb{Z}_{14} \rightarrow \mathbb{Z}_{14}:

f([a]_{14})=[a]_{14}\cdot[4]_{14}; $

confused need help.