2(x +4)-6(q/9)
The slash represents a division sign.
These functions are in the form y=mx+b
Therefore, we know that in g(x) = x+2, the y-intercept is 2.
For f(x) = x-1, the y-intercept is -1.
Now find the difference between them.
2-(-1)= 3
The y-intercept for f(x) is 3 units below g(x)
Knowing that cos(45°) = 1/√2 is the way forward.

The last step in the equation may not be obious, but the trick here is to multiple numerator and denominator with (1-√2), then the denominator has the special product (a+b)(a-b) = a²-b².