Help me i’m struggllinbggg with this

What are the domain and range of the function? f(x) = -4 (sqrt)x

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 i have 20$ and i gave 5$ away how much i got