Question: 2015 Fall Midterm - 5
Consider strings of length 99 consisting of the characters $a$, $b$, and $c$. How many such strings
are there that start with $abc$ or end with $bbb$?
(a)
$3^{99} - 2 \cdot 3^{96}$
(b)
$2 \cdot 3^{96} - 3^{93}$
(c)
$3^{96} + 3^{96}$
(d)
None of the above.