Can someone explain this? i know the answer but i don't know how to work it out.

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Lance lived in portugal and brazil for a total of 14 months to learn portuguese. he learned an average of 130 new words per month when he lived in portugal, and an average of 150 new words per month when he lived in brazil. in total he learned 1920 new words. write a system of equations to represent the situation. use x to represent portugal, and y to represent brazil

Which basic geometric term has no width, no length, and no thickness? line b. point c. angle d. plane