1. Problem: Find the value of $k$ given an equation (missing in input). Since no equation is provided, we cannot solve for $k$. Please provide the equation. 2. Problem: If 100 grams of chocolate provide 300 calories, find the calories in 30 grams. Step 1: Understand that calories are proportional to grams. Step 2: Set up the proportion $$\frac{300}{100} = \frac{x}{30}$$ where $x$ is the calories in 30 grams. Step 3: Solve for $x$: $$x = \frac{300 \times 30}{100} = 90$$ Answer: 30 grams of chocolate provides 90 calories. 3. Problem: Find the value of $n$ from equation (missing in input). Please provide the equation. 4. Problem: Given that $a$, 2, 5, and $b$ are proportional, find the value of $a \times b$. Step 1: Since the quantities are proportional, $$\frac{a}{2} = \frac{5}{b}$$ Step 2: Cross-multiply: $$a \times b = 2 \times 5 = 10$$ Answer: $a \times b = 10$. 5. Problem: A person writes 50 words in 30 minutes. How many words does he write in 2 hours? Step 1: Calculate the number of 30-minute intervals in two hours: $$\frac{120}{30} = 4$$ Step 2: Multiply number of words in 30 minutes by 4: $$50 \times 4 = 200$$ Answer: The person writes 200 words in two hours.