You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").
One example: Paragraph- Sent 1: A Republican bid to keep the government open past Friday includes no new money for the construction of a border wall along the U.S.-Mexico border, according to several congressional aides familiar with ongoing talks.
Sent 2: GOP leaders submitted the new offer Tuesday afternoon in an effort to appease Democrats, whose votes are needed to avert a shutdown of federal agencies, several House and Senate aides said.
Sent 3: However, Republicans also insisted on increases in border security and defense spending, including money to repair existing fencing and new surveillance technology to patrol the nearly 2,000-mile border.
Sent 4: Democrats have indicated that they would support such appropriations so long as no money goes toward an actual wall.
Question: Who has to be appeased to keep the government open?.
Solution is here: 1, 2.
Explanation: The question is: Who has to be appeased to keep the government open? The phrase "appease Democrats" is mentioned in Sent 2, about accepting offer that is mentioned in Sent 1 to "keep the government open". So, Sent 1 and Sent 2 are the sentences needed to answer this question.

Now, solve this: Paragraph- Sent 1: What happens when two forces act in opposite directions?
Sent 2: Net force is the difference between the two forces.
Sent 3: In other words, one force is subtracted from the other.
Sent 4: Think back to the book example.
Sent 5: One force was opposite the other.
Sent 6: The forces were equal in each direction.
Sent 7: In this case, the net force is zero.
Sent 8: Because the forces on the book are balanced, the book doesn’t move.
Sent 9: It does not fall to the ground.
Sent 10: The table is not breaking.
Sent 11: The book is not falling to the ground.
Sent 12: Both are evidence that the force are balanced.
Sent 13: Situations like these are common.
Sent 14: Can you think of objects sitting on shelves or tables?
Sent 15: These are all examples of balanced forces.
Sent 16: Thanks to balanced forces objects stay where you put them. 
Question: The difference between opposite forces when one is subtracted from the other is called what?.
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
1, 2, 3.