3. An equal number of white bread and brown bread sandwiches are made to sell at a school's tuck shop. These filling are put on the sandwiches at random: tuna; cheese; tomato and cheese; ham. Sandra buys one sandwich at random.

a) Draw a two-way table showing the possible outcomes.
b) Determine in the probability that Sandra took a sandwich:
i) made of brown bread, with ham
ii) made of white bread, without any cheese​