How do I solve a problem like this? I solved it like: 3x-10+2x+20=45 and got x=9 but I was wrong. Can you help me understand what I did wrong? Thank you!

For a school newspaper article, cienna conducted a survey to find out students’ favorite subjects. she polled all the students in mrs. lopez’s advanced dance class. why is her data likely to be skewed? honors dance students are more likely to enjoy dance than students in the general population, so dance may be overrepresented. cienna should have interviewed all the students in the school to get more accurate data. honors dance students are more likely to enjoy dance than students in the general population, so dance will be underrepresented. cienna should have interviewed only every other student in the class to avoid having too many people.

Find an equation of the line perpendicular to the graph.

What is the rotational symmetry of a wheel