Olivia bought 12 identical magazines and her sister bought 12 identical notebooks. The total mass of all the items Olivia and her sister bought was 4.8 kg. Olivia then exchanged a magazine with her sister for a notebook. After the exchange, the total mass of the items Olivia had was 2/3 of the total mass of the items her sister had.
a) Find the total mass of all the items Olivia’s sister had after the exchange.
b) Find the mass of a magazine.