The answer to your question is 514
This is an exponential equation with a starting value of 12000 and an increase of 15% each years.
The following are true:
C. Each year, it increases by 15%
E. The painting's value was 12,000 at the time is was sold.
7.8 = 0.65x
x = 100/65 * 78/10
x = 10/5 * 6
x = 12
Because your question isn't specific or formatted exactly, I cannot guarantee that my answer is what you expect.
√2x - 1 + 2 = 5
√(2x + 1)² = 5²
2x + 1 = 25
2x = 24
/2 /2
x = 12
Therefore x = 12.
Proof:
√2x - 1 + 2 = 5
√2(12) - 1 + 2 = 5
√24 - 1 + 2 = 5
√25 = 5
5 = 5