Which set notation correctly expresses the solution set to the equation aria-label="31 minus 9 x equals 4"

To solve the equation \( 31 - 9x = 4 \), you can follow these steps:

1. Subtract 31 from both sides:
\[
-9x = 4 - 31
\]
\[
-9x = -27
\]

2. Divide both sides by -9:
\[
x = \frac{-27}{-9}
\]
\[
x = 3
\]

The solution to the equation is \( x = 3 \).

In set notation, the solution set can be expressed as:
\[
\{ 3 \}
\]

So the correct set notation expressing the solution set is \(\{ 3 \}\).