<s>[INST] Mod calculation 
$$10x + 20  \equiv 11 \pmod{23}$$

So I know the answer is $6 \mod{23}$. I understand that we subtract $20$ from each side. But how do we do extended gcd on this?
Can you explain the steps involved?
 [/INST] $$10x+20 \equiv 11 \pmod{23} \implies 10x \equiv -9 \pmod{23} 10x \equiv -9+23 \pmod{23}$$
$$10x \equiv -9+23 \pmod{23} \implies 10x \equiv 14 \pmod{23} \implies 5x \equiv 7 \pmod{23}$$
$$5x \equiv 7 \pmod{23} \implies 5x \equiv 7+23 \pmod{23} \implies 5x \equiv 30 \pmod{23}$$
Hence,
$$x \equiv 6 \pmod{23}$$
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