Find the measure of the indicated angle

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

Find the center of the circle that can be circumscribed about efg with e(4,4) f(4,2) g(8,2)