Question 308420
Substitute x=4 and x=5 in to each equation. If the equations hold true, then that means that (4,5) is the coordinate of the intersection between the two lines, 2x+3y=23 and y+x=9.


Eqn 1: 2x+3y=23
2(4)+3(5)=23
8+15=23
23=23


Looks good!


Eqn 2: y+x=9
4+5=9
9=9


It's also true. Therefore, the solution of the system of equations is (4,5), meaning the two lines intersect at that point.