Someone please explain how to do this question

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

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 360, a standard deviation of 4, and a margin of error of 2.5%

Bernice paid $162 in interest on a loan of $1800 borrowed at 6%. how long did it take her to pay the loan off?