What doesthe mathematical expression 2 ∈ v means

What term makes it inconsistent y=2x - 4 ?

Which equation represents the function on the graph?

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”?