The use of 'equation' in this sentence

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hi

Could you please explain to me the use of ‘equation’ in this sentence?

Many thanks,

Tom

2

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Equation = ‘A complex of variable elements or factors’…

3

Many thanks, MM.

But I need some more light here. Could you please explain the sentence a bit?

Tom

4

Hi Tom

I’d say it means that various characteristics of the friendship had changed – more of one aspect, less of another, for example.
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