12. of the following, which one is an observational study? a. asking hearing-impaired people to try a new style of earphone to get their opinion b. comparing survival rates between treating bone cancer with surgery versus treating it with radiation c. recording the daily output of a balloon factory for 6 months d. polling people on their favorite color i believe it would be 'c', yes?

What is the slope of the line that contains the points (4,8) and (9,8)? what type of line is it?

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 3 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30∘c on monday, but decreased at a constant rate in the next 3 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.