Whats a common mistake with linear angles?​

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

the coach can choose 4 members to send to competition in 1680 ways. the correct answer between all the choices given is the second choice. i am hoping that this answer has satisfied your query and it will be able to you in your endeavor, and if you would like, feel free to ask another question.