Julianna is x years old. her sister is 2 years older than her. her mother is 3 times as old as her sister. her ucle rich is 5 years older than her mother. write and simplify an expression representing rich's age

Donald is studying the eating habits of all students attending his school. he samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. he then collects data from the sample. which type of sampling is used? select the correct answer below: systematic sampling convenience sampling stratified sampling cluster sampling