Solution of Problem 2

First, convert the message to its corresponding number values,

16 18 15 6 9 19 2 15 18 9 14 7.

Then, divide the string into groups of three,to obtain:

16 18 15 6 9 19 2 15 18 9 14 7.

Form $3\times 1$ vectors and multiply them by $B$, to obtain the encoded message:

116 118 161 77 80 105 85 98 94 74 79 94.