I'm new to statistics and I ran into this question, what I know is $Y=A + BX$ but in the question the value of $B$ is negative, is it normal for the $B$ value to be negative? 

Here is the question, you don't have to answer it, I just added as a reference. 

Estimate the value of $Y$ when $X = 30$ for the following regression equation:
$Y = 6.2 - 1.4 X$.