The question stem just gives a ratio: for for every 4 servings of the dish, we need 3/2 cups of pasta. It then asks for an actual number - how many dishes will he need the next time. This exemplifies an important concept in ratio problems: a ratio is not Real numbers.
It is possible that the actual quantities last time were 8 dishes (twice 4 dishes, requiring twice 3/2 cups or 3 cups of pasta), or 12 dishes (three times the same ratio), etc. All you know is that the raiot of 4:3/2 must be maintained. In order to know actual quantities, you need some 'foothold" in reality - some actual number.
That is why stat. (1) is insufficient - we simply do not know how many dishes Malik prepared last time, from which we could infer how many dishes he will prepare next time, from which we could infer the acutal number of cups he'll need to maintain the same ratio of 4:3/2. This missing detail is provided by stat. (2), which is why we need both statements.
