23 points can you show your work as well as anwser this problem

Uanita borrowed $600 to purchase a new computer. she was charged 7% interest for two years. she used the simple interest formula to find the interest. i = 600(7)(2) what error did juanita make and how will her error affect the interest she calculates? explain.

How many $20 bills do you need to have to make $280

There are 45 questions on your math exam. you answered 810 of them correctly. how many questions did you answer correctly?