My daughter needs on these two questions and i have know clue what the answer is or how to explain the answer to her.

Lilianna uses 3/4 calories per minute just by sitting. she uses 1 more calorie per minute by walking. lilianna uses a total of 12 1/4 calories walking to the park. lilianna uses the equation, d(.75+1)=12.25 to represent the situation. what does the variable d represent in the equation?

If x = ∛200, which of the following inequalities is true? * 2 < x < 4 3 < x < 5 6 < x < 6.5 4.5 < x < 5.5 5 < x < 6

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.