The sale ad read: "Buy three tires at the regular price and get the fourth tire for 3 dollars." Sam paid 240 dollars for a set of four tires at the sale.  What was the regular price of one tire?
$\text{(A)}\ 59.25\text{ dollars} \qquad \text{(B)}\ 60\text{ dollars} \qquad \text{(C)}\ 70\text{ dollars} \qquad \text{(D)}\ 79\text{ dollars} \qquad \text{(E)}\ 80\text{ dollars}$
Let the regular price of one tire be $x$.  We have 
\begin{align*} 3x+3=240 &\Rightarrow 3x=237 \\ &\Rightarrow x=79  \end{align*}
$\boxed{\text{D}}$
Good Job!