u/CommercialLet8392

https://youtu.be/YlmpN5ip3Ko reference video, i dont understand why this guy took a_0. seems arbitrary to me, why a_0?

also i know the standard method of reduction by subtracting s/3 so dont mention it nd waste time.

whats wrong with my answer (i know answer is 3/2 but i followed the exact same method, only chose different notation. different notation shouldnt change the answer if the method is correct.)

so explain why a_0 nd not a_1 (i took a_1)