Questions like this ("how much higher is x than y?") are answered by computing the ratio of the two quantities.
In fact, for example, the answer to "how much higher is 10 than 5?" is 2, because 10:5 = 2, and indeed 10 is twice as much as 5.
So, we have
So, the melting temperature of platinum is about one time and a half higher than the melting temperature of gold.