Had you been louis pasteur what would have been your reflections and conclusions based on the broth & left open flask experiment

Based on the broth left on an open flask experiment, wherein the boiled broth was placed in two flasks (one flask with straight neck and the other flask has a bent neck) and exposed to open air at room temperature for several weeks.

The broth within the straight neck flask has changed its appearance. It became discolored and cloudy. Whereas, the broth in the bent neck open flask still remains the same.

These results would then support the conclusion that germs in the air were able to fall unobstructed towards the straight neck flask and contaminate its contents. While, the bent neck of the 2nd open flask acted as a trap for the germs, preventing the germs from contaminating the broth. Further emphasizing that germs can only come from other germs and not from spontaneous generation.

In this sequence first term(a)=54
and common dofference(d)=-72
so 4th term is a+3d=54+3(-72)=54-216=-162