If a certain negative number is multiplied by six, the result is the  same as 20 less than the original number.  What is the value of the  original number?
Let the number be $x$. We know that $6x=x-20$. Subtracting $x$ from both sides gives $5x=-20$. Then, dividing both sides by 5 gives $x= \boxed{-4}$.