21x+7y=42
-5x+5y=10
x=
y=

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

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”?

What is the perimeter of an equilateral triangle if each side is (x+3)?