Answer
H; $98$
Work Step by Step
For the average of your five scores to be $90$, add them together and divide by $5$. Since we do not know the score of your fifth test yet, we can set up an equation to see what you need to get on it to have an average score of $90$.
$\frac{78+85+97+92+x}{5}=90$
$\frac{352+x}{5}=90$
Multiply both sides of the equation by $5$.
$352+x=450$
$x=450-352$
$x=98$
You will need to score a $98$ to have an average of $90$ on the five exams.
