Solve equations: 2) 2~ 20-3금 ,31 6) 3,45 • (2,08 - k) - 6,21.

Let's solve the provided equations one by one.

Equation 2: \[ 2 \sim 20 - 3 \text{금}\] It seems that there's a misunderstanding in symbol representation here. It looks like you're using a symbol (~, 금) that may not be standard. If we interpret this equation as a mathematical equation involving numbers, you might mean something like:

\[ 2 \cdot 20 - 3k = 0 \]

If so, we can solve for \( k \):

1. Calculate \( 2 \cdot 20 \): \[ 2 \cdot 20 = 40 \]

2. Substitute back into the equation: \[ 40 - 3k = 0 \]

3. Rearrange the equation to find \( k \): \[ 3k = 40 \] \[ k = \frac{40}{3} \] \[ k \approx 13.33 \]

Now, if this interpretation is incorrect, please clarify the symbols used.

Equation 6: \[ 3.45 \cdot (2.08 - k) - 6.21 = 0 \]

Let's solve for \( k \):

1. Start by rearranging the equation: \[ 3.45 \cdot (2.08 - k) = 6.21 \]

2. Divide both sides by \( 3.45 \): \[ 2.08 - k = \frac{6.21}{3.45} \]

3. Calculate \( \frac{6.21}{3.45} \): \[ \frac{6.21}{3.45} \approx 1.8 \]

4. Substitute back in: \[ 2.08 - k = 1.8 \]

5. Rearranging gives: \[ k = 2.08 - 1.8 \] \[ k = 0.28 \]

Final Answers:

For the first equation, assuming the interpretation is correct: \( k \approx 13.33 \).

For the second equation: \( k = 0.28 \).