Guys I'm struggling in mathh :( I need help

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?

Maria heard on the radio that the high temperature that day would be to determine the temperature in degrees celsius, she used the formula , where c is the temperature in degrees celsius and f is the temperature in degrees fahrenheit.

Cesar bought 7 items at the candy store. he bought candy bars for $0.50 each and packs of gum for $0.95 each. he spent a total of $6.80. what system represents the solution for the number of candy bars (x) and the number of pack gum (y) purchased?