Question: 2014 Winter Final - 22

I flip a fair coin, independently, 10 times, resulting in a sequence of heads ($H$) and tails ($T$). For each $HT$ in this sequence, you win \$3. Define the random variable $X$ to be the amount of dollars that you win. For example, if the sequence is $$ HHTTHTTHTT, $$ then $X = 9$. What is the expected value of $X$?