Decide whether each function is linear or nonlinear from its graph

Me because some of question i don’t understand

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

If you are trying to move an attached term across the equal sign (=), what operation would you use to move it?