From "Exemple 3", we know that, for x = 2, f(x) = g(x).
And the y coordinate of point with x = 2 is the value of the function at x = 2:
y = f(2) = g(2)
So, one way to find the y-coordinate, is by replacing x by 2 in the expression for f(x) = 3x + 2:
y = f(2)
= 3 * 2 + 2
= 6 + 2
= 8
Another way to do so is by replacing x by 2 in the expression for g(x) = -x + 10:
y = g(2)
= -2 + 10
= 10 - 2
= 8