For this case we have the following equations:
f (x) = 2.8x - 12
g (x) = 5.8x + 9
We must equalize the equations.
We have then:
f (x) = g (x)
2.8x - 12 = 5.8x + 9
We clear x:
x (5.8-2.8) = -12 - 9
3x = - 21
x = -21 / 3
x = -7
Answer:
The x-coordinate at the point of intersection for these equations is:
x = -7