Explain how 500 thousands less than 2.845 is figured out

(note i put the graph in so plz )the graph shows the amount of water that remains in a barrel after it begins to leak. the variable x represents the number of days that have passed since the barrel was filled, and y represents the number of gallons of water that remain in the barrel. what is the slope of the line

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

Find the solution(s) to the system of equations. select all that apply y=x^2-1 y=2x-2