1-2(5+3х)=15

Let's solve the equation step by step:

1. Start with the original equation: \[ 1 - 2(5 + 3x) = 15 \]

2. Distribute \(-2\) through the parentheses: \[ 1 - 10 - 6x = 15 \]

3. Combine like terms (1 - 10): \[ -9 - 6x = 15 \]

4. Add 9 to both sides of the equation: \[ -6x = 15 + 9 \] \[ -6x = 24 \]

5. Divide both sides by -6: \[ x = \frac{24}{-6} \] \[ x = -4 \]

So, the solution to the equation \(1 - 2(5 + 3x) = 15\) is: \[ \boxed{-4} \]