Which shows the best use of the associative and commuative properties to make simplifying 2/7-17+6-5/7+1

Whats the name of the vertical axis

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.

Astudy was interested in determining if eating milk chocolate lowered someone's cholesterol levels.ten people's cholesterol was measured. then, each of these individuals were told to eat 100g of milk chocolate every day and to eat as they normally did. after two weeks, their cholesterol levels were measured again. is there evidence to support that their cholesterol levels went down? how should we write the alternative hypothesis? (mud = the population mean difference= before - after)a. ha: mud = 0b. ha: mud > 0c. ha: mud < 0d. ha: mud does not equal 0