Find the point of intersection of these 2 lines : y= 2x+9 and y=4x + 5

Graphing will quickly find the point of intersection, but if you are unable to use a graph you can set the two equations equal to each other and solve for x.

Isolate x to one side by subtracting 5 and 2x from both sides.

Divide 2 from both sides.

The lines will intersect when x = 2. Plug this x value into either of the original equations to get the y value of the point of intersection.

The point of intersection is at (2, 13).

[-12x-13y+13z=15 
[7x-10y-3x=11 
[7x+14y+5z=-5