How do you use a graph to determine wether a system is consistent or inconsistent?

Well, if the graph is steady and unchanging, it means the system is consistent. Say you have a bar graph and the height of each bar is about the same, that means the system is consistent. But, if you have a bar graph where the heights are all over the place, that would represent an inconsistent system.
Hope this helped!

A system of equations that has at least one solution is Consistent
and a system of equations that has no solution is inconsistent
Idk if I'm right but hope I helped

57.14%. You could use a factor puzzle, 
since 75 is 100% you put 75 next to 100 on the factor puzzle and put 40 under 75.