4, 3 + 7, 9 - 2, 3 + 2, 1

To solve the expression \( 4.3 + 7.9 - 2.3 + 2.1 \), let's break it down step by step:

1. Add \(4.3\) and \(7.9\): \[ 4.3 + 7.9 = 12.2 \]

2. Subtract \(2.3\) from the result: \[ 12.2 - 2.3 = 9.9 \]

3. Finally, add \(2.1\): \[ 9.9 + 2.1 = 12.0 \]

Therefore, the result of the expression \( 4.3 + 7.9 - 2.3 + 2.1 \) is 12.0.