I could not follow how to solve this

Dear Student, Just go by definition of this question. No need to get into the formula. You know the definition of Km value. It is the substrate concentration where velocity of reaction is half the maximum Velocity. In this question, maximum velocity is 77.2. Half of maximum velocity would be approximately 38.6. So, Check the table now. The nearest value to 38.6 is 38.1 where the substrate concentration is 200. So, Km value is 200. So, the answer is option (1). Regards