Explanation:

- Let's determine the original number. Let $x$ be that number.

- 30% of $x$ is equivalent to $0.3x$.

- Given that $0.3x=135+15$, which simplifies to $0.3x=150$.

- Solve for $x$ by dividing both sides by 0.3: $x=\frac{150}{0.3}=500$.

- Next, find 50% of this number: $0.5\times 500=250$.

- Evaluate the options:

- Option 1: 200

- Option 2: 210

- Option 3: 230

- Option 4: 250

- Hence, Option 4 is correct: 250.

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