An bought a blazer for $39.90. the price of the blazer was $38. what sales-tax rate was she charged for this blazer?

How do i put 3(x+7) in distributive property

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”?

Ineed to know how to write question one in mathematical terms