To solve the equation \( 2x = 20 \), we first isolate \( x \):
- Divide both sides by 2:
\[ x = \frac{20}{2} \]
- Simplify:
\[ x = 10 \]
Now, using set notation to express the solution, we write:
\[ { 10 } \]
Thus, the set notation for the value that makes the equation true is \( { 10 } \).