Identify the mathematical property, operation, or idea that justifies each sequence of expressions below. then find the value of the expression.

Combined megan and kelly worked 60 hours. kelly worked twice as many hours as megan. how many hours did they each worked?

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

In a survey of 1015 adults, a polling agency asked, "when you retire, do you think you will have enough money to live comfortably or not. of the 1015 surveyed, 534 stated that they were worried about having enough money to live comfortably in retirement. construct a 90% confidence interval for the proportion of adults who are worried about having enough money to live comfortably in retirement.