What is the least positive $x$ with $x + 9 \equiv 4 \pmod{12}$?

Explanation

1. 01

   Subtract 9: $x \equiv 4 - 9 = -5 \pmod{12}$.

2. 02

   $-5 + 12 = 7$. Check: $7 + 9 = 16 \equiv 4$.