Answer
It is possible for you to earn a B in the course.
Work Step by Step
To earn a B in your algebra course, you must achieve an unrounded test average between 80 and 90, inclusive.
$80 \leq\frac{78+78+79+x}{4} \leq 90$
$320 \leq 235+x\leq 360$
Subtract 235 from each part.
$85 \leq x \leq 125$
Since 100 is the maximum grade you can earn in the course and on the test, it is possible for you to earn a B in the course.
