Can someone help me please !

Which geometric principle is used to justify the construction below?

Graph the system of equations. {6x−4y=−244x−8y=−32 use the line tool to graph the lines.

Which of these side lengths could form a triangle a) 2 cm , 2 cm , 4 cm b) 3 cm , 5 cm , 10 cm c) 3 cm , 4 cm , 5 cm d) 4 cm , 8 cm , 15 cm