x-3,5=2,1

To solve the equation \( x - 3.5 = 2.1 \), you need to isolate \( x \).

1. Add \( 3.5 \) to both sides of the equation:

\[ x - 3.5 + 3.5 = 2.1 + 3.5 \]

This simplifies to:

\[ x = 2.1 + 3.5 \]

2. Calculate the right side:

\[ 2.1 + 3.5 = 5.6 \]

Thus, the solution is:

\[ x = 5.6 \]