Wrong. a and b cannot be just any values. There is an exact division on a line segment where the golden ratio works. 9/5 does not = 5/4.
You have it wrong I never said 9/5=5/4. What world are you in? That is not what the golden ratio is. Read my post again.

The reason I can say it's the same value is because in between those numbers the golden ratio proves there will always be the same proportion existing. It's another way of saying numbers can be divided to any value from any amount present. So 4 and 5 must hold the same amount if that is even possible. Otherwise they couldn't be divided identically with the same result with the same value in this way. This is proved through the proportions stated which can be measured against the numbers themself mathematically.
Even though it would take an infinite number of divisions to get the same value. The golden ratio itself can be measured from the numbers themself as existing so we know that it's possible.