Not sure where to post this question or what type of question it is

If 66x=10 and 56x=1 what does 61x=:confused:
IF this were "normal multipication" then the first equation would tell us that x= 10/66= 5/33. But 56x= 56(5/33)= 280/33, not 1 so this is not "normal multiplication but, presumably, some other operation. Unfortunately, given only what is written here, there are an infinite number of such operations.
 
Hello, bondi!

I assume this problem involves Modulo Arithmetic.
I can't recreate all my steps, but here is my solution.

\(\displaystyle \text{Given: }\,66x =10\,\text{ and }\,56x =1,\;\text{ find }61x.\)

\(\displaystyle \text{From }\:\begin{Bmatrix}66x \,\equiv\,10\text{ (mod b)} \\ 56x \,\equiv\,1\text{ (mod b)} \end{Bmatrix}\;\text{ I found that: }\,b =13\)

\(\displaystyle \text{Then: }\:66x \equiv 10\text{ (mod 13)} \quad\Rightarrow\quad x \equiv 10\text{ (mod 13)} \)

\(\displaystyle \text{Hence: }\:61x \:=\:61(10) \:=\:610 \)

\(\displaystyle \text{Therefore: }\:61x \:\equiv\:12\text{ (mod 13)}\)
 
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