Posted by **Francesca** on Tuesday, October 11, 2011 at 7:55pm.

Find the value of x:

20x ≡ 9 (mod 15)

- Math -
**Steve**, Wednesday, October 12, 2011 at 4:58am
Let x=1

20 ≡ 5 (mod 15)

As x increases by 1, the residue increases by 5, so no integer value of x satisfies the equation.

If you allow rational values for x, then it is easy to find many such x's: 9/20 comes to mind first...

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