A brother and sister sold magazine subscriptions for a school fundraiser. the sister sold 5 fewer than twice the number of subscriptions her brother sold. they sold a total of 52 subscriptions. how many subscriptions did the brother and sister each sell?

It costs 4.25 for 1 pound of roast beef. how much will it cost to purchase 2.5 pounds of roast beef? round to nearest cent

Plzzz answer both questions and i will give you 100 points

Stu and ambrose are working together on a study of whether diet is related to students' mental health. first, they randomly select 10 students from the student center and 10 students from the office of counseling and psychological services. then, they ask students to rate their diet in terms of healthiness on a scale of 1-100 before completing a 20-item mental health survey. a) name one of the constructs being studied b) how was the construct you named above operationally defined in this experiment? e) was the variable you described above their independent variable, their dependent variable, or a controlled variable? d) what is a confounding variable? what is a potential confound in this study?