If by "coincide", in other words this is also known as intersect, it means that the solution to the system is that intersection point. For instance, if the intersection point of the 2 lines is (5,7) on the graph, it means that in both equations, x = 5 and y = 7. If you mean that the 2 equations result in the same line, it means that the 2 equations were really equal, but that one could be basic to be identical with the other. For example, if you have 2x + 2y = 8 and 4x + 4y = 16, they will give you the same line, and you can see that if you divide that second equation by 2 all the way crossways, it merely shows the first equation.
When 36 people are seated the room is 2/3 full.
So for 1/3 , 18 people are needed
It will be 3/3 full if 54 people are present
So there can be 54 people in total
Now for the room to be 1/2 full , people will be 1/2 x 54 = 27 people
According to his calculations, b has a 3/10 chance to win
I've attached the graphs to this answer. I hope they help.
