Please help need answers immediately.

Add the fractions, and simply the result to lowest terms. 2/3 + 2/7= ?

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”?

Which graph shows the solution set of x^2+4-12x/> 0