Answer all 5 questions

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

The total cost of anja’s trip to the dentist was $628.35. she paid a flat fee of $89.95 which included the checkup and cleaning and then had 4 cavities filled, each of which cost the same amount. which shows the correct equation and value of x, the cost of each cavity filling?